I'm in a similar situation with my dad, only he's much more covert. My brother adopted a lot of his tendencies, but went much more brutal with them. I can tell you that the more extreme the reaction, the more they feed off of it. Physical violence is not the answer and will most likely actually make him worse.

First, I would do some research. Know your enemy. Read everything you can about narcissistic personalities, how they operate, what feeds them, all of the seemingly innocent things they do to trigger you. You might be surprised to find what "normal" things you've been accepting. Sometimes just recognizing what's happening makes it lose its power. This has worked amazingly well for me with my dad. I see through all of the attempts at manipulation and they've just lost all affect. It's almost become a game now, just seeing what he'll try today.

Second, If you cannot cut him out of your life, go as low contact with him as possible. If your family isn't supportive, it really comes down to what you're willing to give up. It might be the best thing in the world to get away from all of it, but that's up to you. If you have to live with it, you need to learn to cope with it and protect yourself.

Third, you have to make peace with the fact that you can only control yourself. The best way to stop the behavior is to stop feeding it. Do everything you can to show no reaction, ignore it, don't acknowledge it in any way. This is going to be tough, especially at first because he will keep stepping up his game to try to get a reaction. If you lose it and react, don't beat yourself up, just try harder the next time. If he keeps going and you don't react, he looks like the jerk. If you don't feed it, he will eventually get bored and look for new victim. If he finds a new victim, pass on what you've learned to help them.

I'm by no means an expert, this is all just from my own personal experience and I'm sure others here have more suggestions, but maybe some of this will help you or lead you in a new direction.