Leave.
I left full time teaching three years ago, after posting on here in utter despair, and I honestly feel like a completely different person.
I forgot who I was.
I now have my own business, and have time to write, cook proper meals, walk my dogs, have a bath in the evening, work on my new allotment...live, basically.
I do miss the kids, and am toying with doing a bit of supply. But in the current climate, the job just isn't worth it. The powers that be are applying a business model to the intangible chaos of kids - and it's hurting everyone, including the kids.
Just leave. If you have to stack shelves - do it.