Jane, good Lord, that sounds stressful to anyone under any circumstances. I am not surprised you are very worried about it, I think you would be "abnormal" if you weren't. It's just that your PTSD magnifies all of that, as we all know so well.

I had the same thought as OE, if you get there and can get through it, it would help your sense of overall self-esteem and accomplishment, I know if I were in this position I would feel that way if I conquered it. But I realize that is a risk, the rewards would be great but so could the self-recrimination if you failed. I don't envy you

I wonder, is there anyone in the class you have become close enough to who you can confide in a bit, and ask them to be a "support" person during the exercise, who could maybe take you aside if you told them you were about to break down, and "talk you down" so to speak?

I have been told that the supplement L-Theanine, from green tea, is called "nature's valium" because it has a similar effect, but is non-sedating and non-addictive. Might be worth a try if you can find some at a pharmacy or natural foods shop.