I'm sorry you are facing this situation. Here are a few techniques that might help you.

Short-Term Techniques for Dealing with a Difficult Person
Adapted from information in Ch. 4 of Children of the Self-Absorbed: A Grown-Up's Guide to Getting Over Narcissistic Parents, 2nd Edition, 2008 by Nina Brown.

Limit your interactions with the individual as much as possible.
Attempt to interact with the individual in public places or other places where observers are present.
If self-affirmations work for you, use them.
Use self-talk in an attempt to discern what is real and what is fantasy.
Listen to yourself with acceptance; acknowledge your feelings and their intensity.
Avoid revealing or acting on the feelings; your true feelings, revealed either directly or indirectly, may become psychological weapons in the hands of your abuser.
If possible, momentarily dissociate from intense feelings.

Employ protective non-verbal behaviors:

“Avoid eye contact, especially sustained eye contact.
Angle your body slightly or completely away from the [person].
If forced to look at the [person], focus on his ear, his chin, or the middle of his forehead.
Put some physical object between you and him. For example, turn a chair around so that the back faces the [person], or look at him over the top of some reading glasses.
Adopt a relaxed body position. For instance, when seated, have your feet flat on the floor and arms and hands in an open position, and try to keep your breathing deep and even.
Think about something pleasant or zone out.
Keep a neutral or pleasant facial expression, but don't grin (or frown).” (p. 95)

“These behaviors are counterproductive for building relationships, showing interest, and communicating caring and concern, so they can effectively protect you from [the person's] efforts to engage you.” (p. 95) Don't be sullen, sulk, or mumble (adolescent behavior). Don't anger the [person] – that gets them to focus on you more; goal is to tolerate the momentary situation.