What should I do?

I recently have gotten back with my ex after we broke up like 2-3 months ago. I thought things may have changed between the both of us. Although we are back to arguing again every couple days or everyday for a couple days. I know on my end I have done some things to cause these arguments. I really do love him when things are good and we are not in an argument but once we get in an argument I rethink everything again. Was it a good idea I came back? Why do I do this to myself? He will hold what Ive done against me. He also will tell me since when we were broken up I had sex with another guy and he didn't have sex with any girl that he should break up with me for a day go have sex with a girl and then we would be even. Or if he sees me talking to someone as a friend but he doesn't like that person he will make me block them and then tell me he's talking to all these girls to make me mad. He recently has called me all these names durning are arguments. He says I am a "colossal Bitch" , "Ass hole", "cunt", "go fuck yourself", "if I am actually stupid?", "if I'm retarded". Those are the main ones that have stuck in my head. Im not sure what I should do. Ive stuck through every argument we've had to be with him but at the same time this is getting a little ridicules. Im not sure how someone could say these words and then later say "I love you", "I want you to move in" and ect. Someone please help,