First, don’t tell me that the answer is just to “not bottle things up”, because that’s objectively incorrect too. Society doesn’t want you to have any negative emotions. I need to know how to not express negative emotions at all whatsoever unless I’m alone. I know it can be done because it is done in many other people on the planet.
Edit: Ok so I think one of the things I want to try doing next is ask for a med change from my psych provider.
In my experience if you have a toxic boss you clash with, and HR is unwilling to deal with the problem then they are complicit, which is a far too frequent scenario, if at all possible it sounds like a new job would be the best option for your mental health while you talk to a therapist about the situation to find coping tools in the meantime