From the way your mom said "I don't want to hear about that wretched woman." it brings to mind that there is something there, between them, that your mom herself hasn't dealt with. Since she wasn't brought up as her child perhaps something happened as an adult it definently sounds like she was seriously hurt by your grandmother. So undealt with pain is the most likely reason she dosn't want to listen because helping you deal with it would force her to deal with her own. Considering in the other things you said like bankruptcy she's probably in enough pain already that she can't find time to help someone else deal with it. I know it sucks and it isn't an excuse but that's reality alot of times. Some people don't even know how to be there for someone when they've been abused. So you might consider trying to ask your mom more directly. Share some of your feelings of pain revealing some of your vulnerabilities and then bluntly tell her "I need help." or "I need someone to listen to me.". Sometimes all that a person needs is a good slap to the face, like those blunt words, to bring them back to reality and the responsibilities they owe. I know it can be hard to be forceful but sometimes you have to demand what you deserve like a mom who will listen to you and be there for you. How do you feel about that?
I came to react negatively to being happy too. I occasionally punished myself for it but moreso I just suppressed those feelings. Like if I ever felt confidence or happy I'd start telling myself I was worthless as I'd been trained to do thus suppressing them. For me I don't think the worst was getting beaten I think it was more social isolation. When I was about eight for example I met some friends my age and was playing with them. My dad came after me, dragged me back home yelled at me and grounded me for it. When I was 13 I tried to make friends too but that similarly didn't work out and to quote them as stupid as it sounds it was "wrong" and "satanic" of me to want to have friends. That's what hurt the most because I found it alot easier to be happy when I was around people. But whenever I was happy or smiling; you know when your really happy you laugh so my parents would tell me to shut up or stop that etc. And confront me if they seen me smile or being happy and they'd force me to stop whatever I was doing and make me do something else or they'd simply punish me for it. So as I grew older I just began suppressing smiling and being happy to stop the pain but in the process hurt myself because denying that happiness to yourself is even worse. And when I finally realized that it was hurting me what I found helped me most was the fact that I deserve to be happy. After being trained for so long that you don't deserve it, that it's wrong and bad etc. You have to come to understand that those aren't your feelings(the feelings that you don't deserve it or that it's wrong.) your feelings are that it's right and that you want it. Think back on being a kid and those were your feelings right? You instinctually wanted to be happy. I found that at least and I think every kid before they're abused instinctually wants to be happy. The feelings I didn't deserve to be happy, even though I felt it, the reason I felt it was because I was feeling my parents feelings. And they're feelings, what other people think, don't matter. I kept trying to please people, live life my parents way, because I thought I owed them loyalty or that I wasn't able to be in charge of my life or make decisions. But we all deserve to be in charge of our lives and make choices we make mistakes sometimes but we learn. So you have to take charge of your life and say "screw you" to the people who try and control it like your grnadmother was doing. And stop feeling their feelings that being happy is wrong or that you ever deserved to be punished. In the end the only people you owe loyalty to are yourself and the good people in your life. Being loyal to your feelings and desires and stop hurting yourself for being happy and rather enjoying that feeling is not only important it's right. As you set out to follow your feelings and desires it's important to remain aware of yourself and make sure it's a healthy life your living. I mean personally I was so messed up a few of the things that brought me happiness were wrong. Like drugs and alcohol they can bring happiness but they hurt you alot too so it's important to make sure you go after things that truly bring happiness and a better life for yourself. So believe in yourself, your feelings and desires and follow them. There is nothing wrong with being happy and you should go after it nomatter what. You don't have to be anyone's doormat. Your feelings matter too. Which is yet another reason to more forcefully seek what you deserve and what you want like someone to be there for you. I know it's hard to take that weight on your shoulders. I couldn't. I just kept living day to day hoping that somebody good in my life would show up and help me. And I kept hoping that the people that were hurting me would stop or I just kept thinking that if I stopped them it'd only get worse. But none of that stuff is true or right. I had to go out there and find good people and bluntly share my feelings of pain and ask people to listen to me. I had to stop the people from hurting me and shape my own life. The reason I eventually started carrying the weight of my own life is because I just eventually got sick of not having one. And being consumed by depression, fear, pain, etc, that's not a life unless your working to make it better.
I definently get the trust issues your going through. I never really got the thought that I was supposed to be able to rely on and trust my parents. I mean I never could so that thought was never even started. So I learnt to never trust or rely on anyone. Even nowadays I still have some trust issues. I find it really hard to believe in anyone. To take a chance on them. So for me the place to start trusting was within myself. After you can trust and believe in yourself then you can start trusting and believing in other people from a much more stable personality. You also need to deal with the vast majority of the other problems as well because trust in other people requires being vulnerable. And your not ready for that right now. So accept it, understand that it's perfectly alright and reasonable that you can't trust people right now. It's actually a really good thing your not capable of trusting right now because that keeps you from plunging again into trusting someone until you understand it. Honestly if you started trusting people blindly right now without understanding what trust was and working through your issues on it. Those people would tear you apart. The very same thing happened to me. I may have never been able to trust but that never stopped me from reaching out to people and trying and that tore me apart again and again because I didn't even understand what trust was. So my suggestion is to deal with the other things first, get to a point you can trust and be vulnerable, develop trust and belief(confidence) in yourself, and then come back to this problem of trusting other's.
You'll find good people in your life and people to trust I assure you. You talk about your parents and family like there's something special about them. But there is nothing special about parents they're just people like everyone else. And sometimes they can be trusted and sometimes they can't. Sometimes they're loving and good and other times they're not. Just because they aren't trustworthy or aren't loving has absolutely "zero" impact on the abilities of trust and love within other people around you. My parents aren't trustworthy and can't love but it has no effect on the abilities of the other people in my life to be trustworthy or loving. The same applies to you. People like to say that family should love you nomatter what but family are just people, and when they can't love you nomatter what, then there are alot more people out there who can love you nomatter what. So it dosn't matter if your family isn't trustworthy or isn't there for you when you need them. It has absolutely zero impact on other people in your life. There will always be people that you can trust and that will love to help you. I like helping you for example and you can trust me if you take the chance to. The only thing that it does effect is that people like us have a tendency to be attracted to people we can't trust and who can't love us. If your having problems finding people to trust you and love you, I assure you, it's because your attracted to them and the other part is just bad luck. So always pay attention to who your attracted to and actively strive to make sure the people you are attracted to "are" trustworthy and capable of loving you. You'll learn more about how to do that as you gain experience. And remember that you are not responsible for how other people treat you you can only try and treat them well and hope that they're willing to do the same. Your mom not listening to you for example, or your grandmother's abuse, you are in no way responsible for any of their actions. You are completely loveable, and there are alot of people you can trust, you just have to find those people who will love you and are trustworthy. If taking responsibility for their actions isn't anywhere near why you feel unlovable, what is the reason?
I never had a little voice that said I deserved to be abused like you but I did have a little voice that kept telling me I was worthless. And getting over that voice is just a matter of believing in yourself. Coming to like yourself and your life. Happiness is the way to overcome it and then belief in yourself. Trust in yourself and that your opinions are right. The opinion that will stop that little voice, once you can believe in yourself is that no kid deserves to be abused. I don't personally care what the kid does it's wrong to abuse them. I for example accidentally broke a watch when I was 4 or 5 and I got beat for that. I didn't deserve it. You didn't either, you don't deserve to walk on eggshells as you put it around people like your family. You deserve to be yourself, to make mistakes, to learn and be happy without fear of punishment. And to be a kid. Free to be ourselves and express ourselves as we develop.
Lastly you need alot more than a school counsellor. What you need is a professional therapist to help you work through all those memories and all the problems they're causing. That's the simplest way to deal with it. You need to change your mentality. This isn't something to "cope" with for the rest of your life. This is something to fix so you can have a wonderful life that you just can't wait to bounce out of bed to tackle every morning. Abuse and trauma are not something to cope with or bury and forget they are things to work through. And you can work through them to make a wonderful life for yourself. You are not scarred for life and you don't have to live with this, suffer from it, for the rest of your life. You can shape who you become in the future and who you are in the present. The only thing you can't change are the physical scars and one day you will find someone who will kiss everyone of them and tell you your amazing and beautiful. Your too young to get involved in relationships but that is one of the things that's coming. Anyway, back to dealing with the abuse, there is no single thing that can be done to make it all go away but starting to see a good therapist will really help you cope and work through it all alot quicker than you could alone. So try and find a way to do that. Universities/colleges where people are learning how to be therapists are always recommended as a place for people who can't afford experienced ones, any type of support group would also be awesome. Getting out there sharing yourself and finding who will be there to listen to you and help you may be hard but it's invaluable in forming a support group. Aside from that start working through problems, feelings, and start steering your life to a more positive path. And being devoted to bettering your life and being happy, making yourself happy. Focusing on that rather than alot of the other things teens tend to focus on(such as trying to fit in for example). Become your own person and focus on making yourself happy and healthy(emotoinally) rather than trying to please other people. I suggest reading some good books, a good starter is "Waking the Tiger. Healing Trauma." by Peter A Levine. It will help shed some light onto the trauma, the dreams, feelings etc. I hope some of that helps!