Disillusion and disengagement
You have some unhappy experiences and in no time at all you have talked yourself into hating your job. It happened to me. Yes, I had foolishly sought and taken the wrong job. But I allowed it to get on top of me, seeing nothing but impossible tasks, intractable students and unnecessary paperwork. I was difficult to live with, depressed and bad company in the pub. When I left, the leadership were visibly relieved.
What is the right thing to do?
The best advice I ever had from an education officer was simply: "Tackle it, Gerald". That's what I should have done.
Given the will, the energy and the capacity to learn from colleagues I would still have left that position as soon as was reasonable, but on a high, with handshakes all round.