I'm in and sorry you're having panic attacks. Therapy does that to me too sometimes. I hope everything goes really well. As worried as you are about worst case scenario, it's equally likely that you'll get a best case scenario, and most likely that things will go middle of the road and you'll be feeling a bit better for sharing tonight.

I hope you'll plan something to pamper yourself afterward, hot chocolate often works for me, or going out, or whatever you find comforting, distracting, or fun.