What does an ex mean when he says he is not over you and gets with you for one night but then does not call the next night and totally ignores you the next day?

I would say that he was just trying to get sex from you. That would be my first though. But it could be that he is just confused right now. The only way to know for sure is to ask him and talk to him about our relationship. And stop having sex with him until you're sure what is going on. Unless you want to have sex, then it's up to you. It means that you're being used for sex. Don't let them use you any longer. Leave them, forget them, and if possible, never be involved with them again.