Hard time letting go?

I already know that I am pathetic for letting it go on this long, so please don't tell me about it. I have been with this guy for 9+ years. In that time I have found out that he is a hard core drug user, unfortunately after I was already totally in love with him. I let that go...to an extent...for a long time. He finally quit that habit and I thought that things would get better from there. However, at the time, I was working long hours to provide for my family, and being as he had an extensive criminal record, it was very hard for him to find gainful employment, so he stayed at home with our kids. Apparently, he completely hated me for this. He felt that I was trying to keep him as some sort of prisoner and not let him have a life of his own. He pushed me to find daycare, but due to the amount of money I was making, it wasn't enough to pay for daycare and cover all of the other expenses, but also too much to qualify for any help from the state to pay for childcare. He harbored HUGE resentment for that, though I have to admit I cannot fully comprehend why. So he decided, after finding out that I was pregnant and suffered a back injury from work, that he needed to do something for himself, which was move to a far off state. He told me the day he left that he was going, but that he was going to make sure that our family had a better life and send for us as soon as he had things established. We talked everyday he was gone, though, after some time I sensed something was wrong. He did not come home for the birth of his son, because, he claimed, he wanted to save the money for us to come to where he was. Well, exactly 1 month after the baby was born, his mom and I convinced him that it was time for us to join him. 1 week to the day later, he told me that he wanted to break up with me. 1 day later I found out that he had been cheating on me for months. We have been kind of off and on since then though mostly off. He says that he loves me and wants to be with me and raise our kids together but his actions completely betray his words. I told him that after cheating, he could never talk to her again and that he would have to open up all aspects of his life to me if I was ever going to be able to trust him again. He has been almost completely unwilling to do this and I know, I KNOW, that I should just tell him to go **** himself, yet for some reason, I seem to give him chance after chance. I feel like I am finally at the point where I just cannot take this **** anymore and am done with him, but that doesn't change the fact that we have children together. I guess to make a long story long, he just seems to have this power over me that I have a hard time saying "no" to and I don't know how to get through the next 18 years of dealing with him without letting him hurt me again. He lets me down and proves himself unreliable and untrustworthy every time he gets a chance. He is very charismatic and we have so much in common that it makes it really difficult to talk to him without all the old feelings rising up. Though I know that I am just going to regret giving in to those feelings, sometimes, they overwhelm me and I give in. It seems like he wants to keep this control over me. He has told me many times that the longer we are broken up, the more he wants me, and I think that is just because he wants to control what I am doing. He knows that I have been so devoted to him for so long that he just can't let go. I guess my question is, how do I deal with him for the next 18 years without letting him hurt me anymore. At this point, I can honestly say that I hate him for all the **** that he has put me through with seemingly little or no remorse. Sorry if I am rambling but at this point between having a 6 month old baby and little sleep and all the bullshit I have been dealing with, with this "man" I think I have lost my ability to have coherent thought. lol Any advice on this would be much appreciated. Thank you if you have taken time to read this long *** post.