Sounds like a toxic environment! Unfortunately, very many workplaces are.
Learning to realize and accept "it's not you" and to not let it get to you is very hard.

You also have to accept that you cannot change someone else nor their behavior towards you or other people. I've worked with a guy for over 25 yrs and he still treats people like dirt. Then he wonders why he has no friends and no one likes him (I could easily go off on a tirade right now, but I'll refrain! ).

Trying to find that "perfect" fit as far as a career/job goes, I don't know that any one of us has that luxury. Having a job is as lucky as we can get.

Use your therapist to help you with coping skills and self talk or meditation or mindfulness skills or whatever works for you.
Good Luck.