How can I finally let go and ignore him after 3 years?

My ex of 3 years, has cheated on my multiple times, I have lived with him on and off again for 2 1/2 years. H e has kicked me out and and then wanted me back. He has left me for other girls only to want me back, it has happened like 20 times, and I know he wont change but I keep believing him. I now am about to have a baby by him October 16th of this year, he says he loves his son but hes isnt going to be at the hospital cause of his g/f which he cheated on me when I found out I was prego. I cant seem to let go no matter what. I try to ignore him but it doesnt work and I just wind up contacting him. He told me a few days ago he wanted to get back with me and would do anything to prove it. Only when I left his house, to ignore me and call me names and say he doesnt want anything to do with his son. But I have no doubt in my mind in a few days hell say sorry and all that only for my to believe it and then get crushed. I want out but I cant seem to do it even tho I know I should... I just need help

well 4 the childs sake you have 2 try hard 2 make it work between you 2 and it need his support 2 he needs 2 be as devoted 2 you and the child as you are 2 your child and him he must love you if he keeps on wanting you back mabe you need 2 find out why he keeps on leaving and comeing back 2 you ok you are having a baby but mabe you were not sexualy giving him what he wanted mabe he is looking 4 the thrill that he had with you at the begining mabe make him want you so that he wont want 2 go with other girls just you hope this helps in some way

My mom has a simular problem. Except she isn't pregnant. But she has this guy friend that has cheated on her multiple times. Probably about 40 or 50 different times, and she can't let him go. And she doesn't know why either.
I think, he is only doing this because it feeds his ego. You're giving him power over you. And I don't know why you're still letting him. But you just HAVE to be strong and let him go. I know it's hard but just have one of your friends help you. Like have them keep an eye on you and make sure that they don't let you answer the phone for him. And let your friend stay with you for a little while. And that way if, he comes to your house, SHE can tell him to get lost. I mean, he can have visitation rights for the baby. But that will be the only time you see him.
Just be strong and don't let him push you around anymore. He knows he can, and that's why he does it. And he also does it because he knows that you'll just take it and take it and take it over and over again.
He knows he has control over you and he likes that.
Please fun- mail me and tell me what you are going to do about this. I think that this is a REALLY big problem.