Hi mugwump, I do think you have anxiety. I think tms tools from the structured educational program and Alan Gordon's program can help, but I suggest reading or listening to Clair Weekes to specifically explain how to approach anxiety. She writes about face float and let time pass which I think is like somatic tracking that Alan Gordon teaches.
This is only my opinion, I am not an expert, but I think your brain has a "habit" that you are in danger when you are groups. You can slowly teach it you're safe.
Something that has helped me is to remember that if I practice these techniques and it takes awhile, time will pass either way. I am doing a good thing for myself even if it doesn't happen quickly. I also heard someone say when asked when will it start to happen, as soon as you begin the journey, you are changing.
Lizzy