Thanks for the responses so far. I'll try to address some of the questions/suggestions.
I can't collect unemployment if I leave voluntarily, unless I can prove that I had no other choice but to leave. While I think my supervisor is a bad manager, I don't think I can prove that she has been abusive.
My current pay is okay, but nothing exceptional. The only good thing is that I have a 4 day schedule, so I get more time off which is nice. If I have to start working 5 days, I'd make more money for sure. I've been working here for 5 years, which I think is too long anyway. It was never meant to be a permanent job, I just got comfortable.
There is a potential to switch to another department, I'd have to apply though and I think I'd rather just be in a new workplace and have a change of scenery. I don't have very many coworkers, and the job is very isolating. Other people realize how crazy my supervisor is, but they don't have to deal with her as directly as I do.
I think I should look into therapy, talking through the problems would probably help. My work has a program for a few sessions of free counseling, I could take advantage of that before my contract is up.
@bbates728 I really appreciate hearing your perspective and experience. I think I will be better off if I leave, it's just making that leap that is terrifying, since it feels like I'm leaving for something unknown. I would feel better if I had something lined up, but I'm finding it really difficult to search for work through this foggy lens of "everything sucks, I'm no good, no one will want to hire me". I know I can be a good worker, I have education and experience that I am not using to my full potential, but I feel so stuck here.
I know this is what FU money is for, and I think I'm just looking for confirmation and encouragement that I'm making the right call. I think I'm going to immediately put any unnecessary expenditures on hold to have the maximum cash available to tide me over, and give myself a hard deadline of non renewal of this contract. That means 6 weeks to save, get therapy, reset my head and start looking for a new job.