Where can I find the motivation to work this out?

He cheated as he said it was my fault because I didn't spend enough time with him. I cared for our child and made up for his shortfalls financially and started to feel resentful towards him. In turn I didn't want to be physical with him. He ended up cheating, he said because I wasn't being affectionate with him. He wanted me to fix my end of the problems yet he didn't want to fix his. He ended up cheating multiple times with multiple women. Now I want to leave him for good as I'm completely turned off by him yet he wants to "marry me" all of a sudden.I would love to have my kids grow up with their father everyday, but I don't see him being faithful for long as I probably won't want to touch him still. How do I get over the resentment so I can even start to try and work this out with him? He didn't do much at all for me and the kids, and since I caught him cheating this time, now he's Mr. Mom, cooking cleaning carpets waking up with the baby ,and all the things he never wanted to do. It seems like an effort for the better on his part, but I just can't subject myself to being intimate with him, and in the end it'll cause him to cheat once again. What do I do?