can my husband really change?

My husband and I have been together for nearly 8 years and married for 5. I am 30 and he is 37 and we have a 2 1/2 year together and an 8 1/2 year old that is mine from a previous relationship, but whose father has never been in the picture.
Our relationship has been troubled throughout and downright unhealthy since we got married. My husband has been always extremelely emotionally and verbally abusive, often calling me stupid, idiot, dumb, incompetent, incapable on a daily basis. He likes to tell me how to do everything and if I do it "wrong" I am criticized and ridiculed. He often calls me a bad mom, though he rarely helps out with the kids. I have caught him video chatting with women throughout our relationship, as well as emailing and talking on the phone and each time I confronted him about this he has argued that the only reason I have a problem is because I'm insecure. Meanwhile, he often withholds sex and affection from me, saying the more I want it, the less he does. He also quit his job 3 weeks before our wedding and didn't get another full time job until this past June. He decided to get rid of his car 3 years ago and started driving mine, which I paid off 2 years ago. He takes it to work everyday while I drive an old car of my mom's that is on it's last leg and has no air or heat.
I could go on forever about the troubles we have had and the things he's done that have led me to fall out of love with him.
About 2 months ago I began making plans to leave, but decided not to tell him for fear he'd kick me out immediately. However, about a month ago I further complicated things by becoming involved with another man, and a few days ago the relationship became sexual. I am not proud of this, and justify it by telling myself I would never have done it if I was not done with my marriage....but still I know it's wrong.
The guilt if all this got the best of me and a little over a week ago I told my husband I had had enough, was no longer in love, and was in the process of finding another place. Well, he flipped out, started crying and begged me to stay. He swore he'd get help and that he knows he's been a terrible husband. He said that was his wake up call and he thinks we can work on things and get better than ever. In the past week he has been giddy and affectionate and we've had some great talks.....despite the fact I've continued to be upfront about my lack of feelings. The problem is I really feel like I've been burned too many times to ever fall in love with him again. And also don't believe he can truly change for good. However, at the same time I feel like I owe it to the kids and him to give him a chance....even though my heart isn't in it.