That sounds really hard, growli. I don't think there's anything wrong with that class per se, but it sounds pretty dangerous for you right now. I agree with others who've said, talk to your professor, and the head of the department if necessary, with your T's support. Ask if perhaps your T can accompany you to a meeting with them to help explain why it's not a safe class for you to take at this moment. It doesn't seem like an overreaction at all, and my guess is they'd be willing to either: provide another class to replace that requirement, or at least let you put it off as long as possible, to enable you to get more therapy under your belt and be more prepared for that kind of exposure.

Don't beat yourself up for it--this is one of those stressors you can prevent, so be an advocate for yourself and make it happen!