My one piece of advice is polish up your resume and look actively for a new situation. I have been in your position, and my experience has been that either something happens to sabotage the situation (it’s about 50-50 my fault to someone else’s) or my body literally starts to break down. Misery (for me) is not survivable. You say you’ve had to resort to medication so my guess is you are similarly wired.
I can take it a whole lot longer though, and with a lot more aplomb if I am actively seeking a better job. My physical symptoms are reduced significantly when I stay in the solution.
Like the “stay in solution” way of framing it. In a similar situation myself : public school employee, difficult environment & circumstances, mid-fifties, on anxiety meds. Too much invested at this point to realistically do anything else that will give me the pay & benefits I now have, so I gotta just suck it up, basically until I can retire, assuming I can make it. Yes, absolutely get your resume together & keep looking. The only additional advice I could offer in the meantime would be to try & practice self-care as much as you can. Sounds simplistic, but make sure you get exercise, eat right, get enough rest, get outdoors, cultivate outside interests, get into therapy, pray/meditate if so inclined. If you’re part of a union talk with your rep about it, though I know the effectiveness of that can vary widely. Have lunch with colleagues. Commiserate, bitch & moan as needed, but then try & focus on gratitude as much as ya can. Hang in there & good luck!