I had a boyfriend 8 years ago who beat me up and was emotionally abusive. I still thinking about him and I can’t get out of this nightmare. How do I stop them?

It has been seen many times that the abused people are wrongfully clung to their abusers. It is absolutely not a good thing. You have ended that relationship of yours 8 years back and you still get those horrifying nightmares? This clearly shows how bad your relationship was and how wrongly you were treated. If you are still having a hard time forgetting those awful memories, consult a therapist. You need to get out of that cycle and treat yourself better. You deserve a happy and good life in a safe environment.