This may be rude, but I think you need to be alone for a while and not to get with anyone Focus on other stuff, focus on your studies or other hobbies and try to make genuine friends.

I’m simply failing to understand why you kept on going back to that abusive even though you knew he was no good for you? Was it because you were afraid of being alone? Not getting back with him should have been a no brainer. I have no doubt he’ll try to come back, but you have to say no to him this time.

To me, it seems like you over complicate things for yourself by getting involved with too many people at once. I agree with Anita, that you should end it with all three. As I said, focus on other stuff. This will help you learn about yourself and perhaps find out what kind of person you want to be with.