My previous workplace, last year, was very toxic

They shunned me so much, I lost all faith in myself. I know I'm not the best at my job, but am I truly the worst? They convinced me to give up, officially. I was extremely broken. I was told I'm a horrible person/character and far from a delight to work with. The bosses isolated and bullied me. I felt so troubled, that I still suffer from extremely negative thoughts surrounding my weaknesses. I got an email from the head office yesterday, and I had convinced myself it is for the worst. I got an anxiety attack, thinking "they're for sure firing me. What did I do? What did I do? I can't think of anything I did, but isn't that horrible? How incompetent can I be to not even KNOW I did something horrible?"

But it was in fact just a regular email.

I feel so broken and exhausted.

I want to get better at my craft. I try so much to improve. I've even pushed my leaves to get more work time so I can learn.
I feel lost. At night I suddenly get very anxious in my sleep thinking about all the horrible things that can happen because of my incompetence.

Then I tell myself "are you really incompetent to have come so far??"

I wonder when the trauma will go away. I wonder when my performance will get better and I will build the confidence to be more of a leader (required for my line of work).