He may be in personality disorder

Google it! I knew how bad it will affect your family, BTW, it is a genetic thing, see if your uncles, brother, cousines, etc. or any close relatives have similar personality, acturally, it is insane, it is better keeping away from him, he is very dangerous to your mother's life, maybe he will regret later, but he will do it when he feels angry, not because others bopthered him, just he is insane, good luck, if he is still resasonable, then talk to him and let him know he is very sick in brain, if he can't admit it, that is the usually the case for this knid of people, then ask your mother to divorce him for her safe.