As to why you keep getting into bad relationships, it would be well worth your time and money to explore that with a counselor. I'm no counselor but if you were to do some soul searching, you may well have a revelation--or two. Think back to your childhood...what type of relationship did your parents have? I once read that regardless of whether we are male or female, we are attracted to those who remind us of our mothers. How were you treated as a child? Any verbal, emotional or physical abuse? Being treated badly as a child often leaves one thinking that such treatment is normal. Thus when you're out on your own and find someone who treats you that way, you think it's normal.
I think you've made the right start by wondering why you keep cycling into one bad relationship after another. My advice would be to break free of this guy. Then take a break from relationships and get some counseling.