What should i do about my boyfriend?

OK. This is a tough one. As to your question at the end yes it probably was his upbringing that influences his behavior in this regard but that is simply not an excuse. A friend of mine was beaten horribly by his parents damned near every day during his childhood but he has never laid a hand on his girlfriend. While I won't comment on the self-injury his reaction to it was not right. Do a little research on abusive relationships. Once he figures he can hit you and you won't leave he'll just keep doing it. And each time he'll be just as sorry as before. But since you say you love him you'll give him another chance anyway. If you feel you must, lay down some ground rules- if he wants you to stop self-injuring then do so (I assumed this was his position). But make it clear that he is no longer allowed to touch you without your permission. If he strikes you again then leave. There are other men who I'm sure would be glad to have you and would never think of harming you, even in blind rage. I wish you the best of luck and hope you stay safe.