You did a really good job. I don't usually feel paniced afterwards... at least not the same as beforehand, but I do feel agitated sometime and worry that I could have said/done something wrong. I try to focus on the fact that there is nothing I can do about it.
I know it's hard, but try to focus on the fact that you made it. You accomplished something you might have thought never possible before. Think about how much hope this can bring concerning other things you once thought impossible.
You did an amazing job. I'm also working on some similar desensitization stuff. My goal is to someday reach the top of a certain staircase and not think about how I have to go up the other one (OCD related). I reached my first goal yesterday of staying on the 4th stair for 60 seconds and stay relatively calm. I really paniced when I thought of eventually going more but now that I reached that goal I'm trying to focus on the fact that maybe it is possible to overcome this (eventually) and maybe other similar things too.
It's easy to slip back into the mode of "what if _____ (something negative)". Try to focus on "What if _____ (positive)... like What if I can do this. What if I can eventually hang out with friends in public? What if I can go outside without constant worries running through my head? What if I can eventually lead a relatively 'normal' life?
Congrats on your accomplishment and I wish you the best with your next goal. Try to stay focused on all the good that can come from this (not the pain of enduring it in the present). There is a light at the end of the tunnel and you just made one huge step closer to it.
Good Job