Be strong. You have nothing to loose. If I were you, I would choose the divorce. Think about this, this kind of enviroment is not healthy for your son. If the situation won't change, he would turn out to have the twisted personality and unhappy for all his life. Remember, it is not a shame to divorce. Live a life for yourself. It is still not to late to correct the situation. Otherwise, you'll regreat.
I am so sorry for you.