Hi dear Lily ~ I'd be very careful Lily. While he MAY be clean & free of pain, what's going to happen when he drinks? And he STILL has anger issues. Just because he's off the drugs doesn't mean that solved his anger issues.
He needs therapy for that. I'm so GLAD you left him after he hit you. No one should put their hands on another human being. You shouldn't have slapped him either.

Perhaps you could use some therapy too. Violence only begets more violence. And it solves nothing! Perhaps therapy would help you choose someone who is UNLIKE this guy -- so you wouldn't make the same mistake twice.
I really don't think that going back with this man is a good idea. You left him for a good reason. The anger is still there. Find someone UNLIKE him, who will treat you with gentleness, respect and who will love you. I do think therapy might help you. God bless and please take care. Hugs, Lee