wow.. you sound like me almost 7 years ago. i had a similar situation to yours, only when i was pregnant, he found out about the other guy i was with when we were broken up so he denied that the baby was his, and i ended up having a miscarriage.
anyway- i can relate. you have invested so much, you just want back what you give.Those moments when he is sweet are so great you think he will be like that all the time eventually. You always give him the benefit of the doubt, and think that some day he will come around. You dont think you will ever love anyone like that again.... am i right???
Trust me, you need to get over him. Just like you self induce harm by cutting and drinking, you are also self inducing harm by being with him. He is like your drug. you are not in love, you are infatuated and obsessed. It is like quitting an addiction, but now it is not just you, it is also your baby who will be getting hurt. Unfortunately there is no way to make him into the person you want him to be, you cannot make him love you and want you. Do you really want a guy that will leave you and the baby??? Do you want a guy that doesnt want you? don't blame yourself, when you were with that other guy, you and him were not together. and if you are anything like me, you were still together, just having an off period (because you would take him back when he came, and he knew it). But that doesn't matter. All resentment you feel towards him is not going to go away, and he will never begin to understand. Finding out about your relationship in between is just to justify not taking the responsibility of being a dad. You don't want your child around that anyway.
He doesn't respect you, he thinks he can come and go and do what he wants (that is what you have always allowed him to do...) When he says he is sorry, he knows that that is what works for you, but how long are you going to keep believing that? Men don't respect women that don't respect themselves... when you respect yourself, you don't let him treat you in a way you don't like. There is no compromise with that. At this point, you owe it to yourself to treat yourself better. Let him go, as hard as it is.... he will regret it later, but for now take care of you and the baby, I know it must be hard... but now you cant keep on playing these games with him, it's not just about you anymore. You will meet someone that is worth it, that also finds you worth it. It is only a matter of time, you will get over it.
i hope this helps- i learned the hard way and that's what i learned. You are learning the hard way as well.. ask yourself "what have i learned?" and move on.
You went back to him knowing what a creep he can be? With all those red flags I would have to assume that you will be with him until you get sick of the abuse. I do not understand why gals get with guys that treat them so badly and then cll it love. I would suggest seeing a counselor, maybe they would have an answer for ya! I would imagine you are there because you like it. I am not being sarcastic either, just honest. Good luck.