Attending appointments with him is way to much contact post abuse. Legally, I am pretty sure that there is no way that he can decree that you can’t have separate appointments. Like KIP said, speak to the school and make it clear that you need separate appointments for your own safety. You will be a much better advocate for your kids if you are alone too. Is there any way you can reduce your contact with him in other ways too? It will really help with your anxiety I think.