It helps me to make a list of what I want to say. Maybe put on the list something like don't react to the jerk
Practice grounding; feet square on the floor, arms at sides, focus on the feel of the floor and chair. Look around the room and identify details. Maybe count the number of green (or whatever color) things you can see.
If you get triggered, imagine that you are watching a train go past and the trigger is on one of the train cars. It goes out of sight quickly.
If you trust your lawyer to represent you well, you could focus on saying the alphabet backwards or counting backwards by 3s from 100 to distract yourself.