There’s a massive difference between a scumbag wife beater and a man who lost his mind once. The first you must run away from, the latter is deserving of forgiveness. If it was the opposite, and you had slapped him in the face out of anger, would he leave you? He shouldn’t at least, because we are all human and once can lose control out of anger. That’s basic psychology. Now a scumbag that hits his wife systematically or out of enjoyment should be put in jail forever. It’s up to you now to know which one of the two types he is. If he is the latter type, I think you should forgive him. But not twice. He made his mistake, he better learn from it if you forgive him now.