When your work makes you ill then it is time to reassess what to do. Basically either get support and coping skills that work (may not be possible - then again it might) or change jobs, or frequency of going to work.
I didn't reassess, kept going until I stopped functioning, then invalided out with PTSD, depression, chronic anxiety. I am now quite good, but permanently out of the workforce - of any sort - except voluntary.
Mark and Paul have, as usual, given pretty good advice. Mark is a great example of someone who was struck by PTSD, anxiety and all the usual suspects, but has recovered to the point where he is back at work. Anxiety and PTSD can indeed be overcome by some. (sorry to talk about you Mark - don't mean to be rude)
My son works in A&E, but a few years ago, before things started to build up too much, made a conscious decision to work part time and study too. Gave him 2 different worlds, lessened the pressure. Made for perspective.
My first wife was a casualty sister. After a number of years she changed to the more relaxing pace of X-Ray for a while.
I tried to beat things on my own, did not work. I tried ignoring the basic problems, that did not work either. Your symptoms and situation are quite familiar to me.
So what am I saying? If I was in your shoes I'd start by ensuring I had the best medical treatment available.
Normally that starts with a GP, assessment, and then possibly meds and visits to a psychologist to give you the tools to cope with, and minimize, anxiety. The Smiling Mind app Mark mentioned is very useful, I have it too.
I'd also consider a slight change of path. If part time is not practical than another department, or agency?
Seeming calm capable and confident on the outside is fine, but please don't let life erode you inside.