Can you ask your T if he/she can help you slow down the upset that you are going through so that you can manage work/life balance while still work on the flashbacks ?

I know it is not fun to get a poor performance review - often a manager will offer a "plan" for improving performance. Did your manager make any such offers ?? Sometimes it helps managers see a person's potential if that person approaches them with a "plan". It sounds as if you were not aware of some of the issues that your manager had about your performance - it is difficulat to effect a change if you don't know the change is needed.

I am so sorry that all of this is happening to you. Hang in there, this is just one person's opinion of your work effort.