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.
Yes I have very recently. It is currently an ongoing ordeal but I am not hopeful. People have gone to HR about my supervisor before and it has never changed anything.
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
Keep trying, document everything. Get people to talk and align their stories. Consider getting several people with grievances to go to HR together. Showing up together is a show of force most HR take very seriously in my experience.