I sympathize with your situation. Your boss has power over you, there is no question. Yet it is you who decides how much power s/he has.
Before you can make your external situation better, you must make your internal situation better. I will write a full article on it after Passover, but I would just tell you that absolutely no one can make you suffer without your cooperation. In my article, I talk about the professional persona - basically acting out a role, just like an actor in a situation comedy at work. How are you reacting to your abuser? Are you becoming silent and sad, getting red in the face? How would it be if you smiled? Force yourself to smile in his or her face and say, "You're right, doctor. I am [whatever name s/he just called you." My bet is it would take all the air right out of that windbag.
Feeling good under these conditions is another story. I will write an article on it in the next couple of weeks.
I hope you find this helpful. I feel for you in your situation.