Sincere help needed.

I've been with the same man for 5 years now. Throughout the years he's become physically & emotionally abusive. Today was the day I had enough. I told him I was leaving & he dropped to his knees, sobbing like a child begging me to stay. He's promise to call a doctor to get therapy (he has a lot of mental instability) but I still want to leave because he's never changed. I told him maybe a break & with him getting therapy we could give it another go. He said if we take a break I am dead to him. 5 years, I just don't know what I'm going to do.