If you leave him for reals you will not have to witness his destruction. Also, if you leave he might have to really take a good long look at why you left and realize how destructive his drinking is and get real help for his depression.
But, abuse is abuse is abuse. He's abusive, whether he drinks or not. You've tried to help him, It' hasn't worked. You can't fix him. Stay away from him and save yourself. Alcoholism is progressive. Abuse tends to get progressively worse as well.