Jennifer, talk to your 2 therapists and tell them of your difficulties with this person. Ask them to help make the other person stay respectful and non-confrontational. Perhaps at the beginning of the meeting, one of the therapists can help establish the "ground rules" of the meeting: respect for all, listening and not interrupting, no raised voices, etc. The T would brainstorm ideas for the ground rules with the participants and all parties would come up with a list containing everyone's suggestions.

My T fills a role like this at some meetings I have to go to.