I am so much like you, only the elementary version. I don't allow my principal to know what is going on when I am out, only HR, because I am sure she would use this as another thing to use against me. She already uses whatever she can to make my already difficult life a living hell.
Here are some ideas I have used for myself. I have manipulated the fmla days. My pdoc and t are always very cooperative with this because they believe that my job really hurts my mental health. But right now, I can't see beyond the money my family needs.
Like you, I am trying to figure out a way to get out while not losing too much. I am sure I am older and closer to the end of having to be there because I have my own children to get through college before I can seriously consider getting a less stressful job. Have you considered applying to a private school? Perhaps their timeline for finishing your certification needs will be different depending on their needs? If it is like the schools here, the pay is less, but maybe that means less stress. The same goes for charter schools. I worked in one for several years, and the requirements were the same, but I think there was a year's leniency for new teachers to get updated on their certifications. They just had to work at TA pay during that time.
I know you work at the middle or high school level, but have you thought about moving down to the young ones, the preschoolers? I have also done this for a short time. They are cute. It's fun, but you have to have LOTS of energy! It might be good if you are this type of person.
I have taught in more than one state, and the current one I teach in has no respect for teachers. I am surprised that those without problems can survive, and I have no idea how I am making it except with lots of tears and stretches of days either in the hospital or at home with daily visits to my t or pdoc until I am strong enough to face it all again.
I am so sorry you are in such a bad place. Probably the teachers you work with aren't talking about you as much as you think. At least that has been my experience. I hope it is the same for you.
Good Luck and I hope you find quick relief
Bluemountains