Maybe the child is reacting to the toxic environment.
When I was seven my parents divorced. No one talked to me about it. I had to deal with all the emotions all by myself. Years later I realized that alcohol played a big role. Both my parents used alcohol all their lives. I also became an alcoholic. Please find a way to reach your son.
He may have a genetic predisposition, and he isn't going to understand that part at his age. He will understand that things aren't right with dad, and you are trying to find a better way to deal with dad.
Can you get some outside help for you and your son?