Alright breath deeply, in, and think about everything that's happened just keep building it up into a little ball as you breath deeper and deeper. Then hold it and hold it. And then just breath out slowly letting that ball roll away until it's out of sight then repeat keep doing it until your calmer. Right now your consumed by emotional chaos, your head is so full of emotions and thoughts that you can't even think straight. It's been two weeks since you found out and it's well past time you put yourself back together; lean on your friends, family and put yourself back together. Then once your calm and have a clear mind you can deal with what happened.
I'm really sorry for what happened. So lets start; what you need to do is see a sexual abuse therapist, see several infact, to get their opinions and decide your next course of action in regard to your daughter. She needs help or this will have repercussions later on. But a therapist will know how and the best way to do it and especially when the therapy needs to happen. Considering the repercussions won't likely come into light until much later in her life as she begins to grow up sexually. The good news is months are much better than years so don't blow things out of promotion, while it is very serious, it could honestly be much worse. This isn't going to ruin your daughter's life especially not with professional help. The best thing you yourself can do is stop being the source of emotional chaos by putting yourself back together and being calm, clear, honest and loving with her. Don't smother her or be overdramatic or chaotic just be stable that's what every child needs regardless of the situation.
Once you take care of your daughter then you can deal with the rest. However much it might feel like it's all your fault it isn't. People make mistakes and that's all right. And the person to blame is your ex so just let him go and let the police handle it. The rest is about you. Your sex life with your ex dosn't mean anything. Just because a guy isn't getting sex dosn't mean he'll go and molest a child. If he wants to molest a child he'll do it regardless of sex. Your mind is just rushing so much your trying to make sense of it and you want to blame this but it's wrong. The amount of sex you two had or lack thereof or the porn have no impact on this. Being a molester is who he was and that's all there is to it. It's not what MEN are, it's who HE was, so accept it and move on. If you start blaming men or thinking of it like that you will have severe issues trusting men later on if you don't already. Just accept that it was who he was nothing more.
I know that you feel guilt and I know why but it's blown out of proportion and it's something for your kids sake that you just need to let go of and deal with. This was not your fault. Lean on your friends and family and deal with the guilt, get past it as best you can. And as time passes deal with it more and more, the sexual abuse therapist for your daughter will be able to help you with this as well as they will have encountered a parent's feeling of guilt many many many! Times before.
I can't explain it but I get the feeling that your attracted to guys like this. Sometimes people are attracted to certain types, abusers, people they know will abandon them, cheaters etc. It's not a conscious attraction but rather a sub conscious one and I think sub consciously your attracted to bad guys. I definently think you should see a therapist regarding this.
I also get the feeling that you have abandonment issues. Did anyone leave your life, dad, sibling, relative, ex boyfriend or husband? And was that leaving traumatic? You should consult a therapist about this as well. You had your boyfriend move in with you way faster than you should have which makes me feel like your desperate and you also have the second part of that problem too which is an inability to be close to someone. The cycle is being desperate for someone and once you get them being unable to be with them and always pushing them away. You also sought to control your boyfriend which tells me you have strong insecurities regarding men in your life. These two things are very characteristic of abandonment. So please see a therapist for everything. Just sit down and talk with one about everything nomatter how minor or insignificant it might seem and let them explore your life so that they can help you. What happened is not your fault but I definently get the feeling you have serious problems of your own that need to be dealt with for your children's sake. Most of all be the supportive and stable person that your kids need in their lives especially your daughter! I really hope that helps and things get better. Good luck.