Sounds very familiar, only I was the wife and he was the alcoholic and angry husband.
Don't hesitate to leave next time; take your son, go stay at a hotel or with friends. Let her know you'll be back when she is sober again. Unfortunately, the more you disengage, the more likely she is to try to engage you again. It can quickly escalate into a dangerous situation, if she is already three sheets to the wind.
When we stop pleasing people, people aren't pleased.