Agree with Chicken Noodle Soup on this. Unless the therapist is a trained workplace mediator, I wouldn’t use a therapist.

As I see it, this is not about your relationship with the other person. To be blunt: your feelings don’t really matter and neither do theirs. You presumably have a right to be accommodated and your coworker/workplace presumably has an obligation to accommodate you.

That’s all the mediator (or just HR) needs to determine and address.