Is he cheating on me or trying to leave me ? :(?

Maybe he is just trying to get to know you better and have a better understanding of your past. That is good to open up about things like that. As far as not hearing from him, do you mean in general or just about this? I wouldn't worry if he stopped talking about the past and being cheated on. Again it was probably just out of his own curiosity and to let you know what happened to him.