I've had quite a few jobs in my time, from the extremely well paid to the very little appreciation kind, and they ALL without exception have challenges.
However, few jobs are as hard as teaching these days.
I started teaching in the seventies, when the whole country was failed and ill educated, as OFSTED would tell us. Somehow, miraculously, people who went through state schools in the seventies managed to become barristers, surgeons - even OFSTED inspectors. However it happened, it happened without beating teachers into lives of misery.
I took break from teaching for many years, and then went back. For a while I couldn't quite take in what a horror of a job it had become.
In another job I had, not teaching, one man became so pressured and distressed because of the ridiculously excessive demands on him that he did eventually kill himself. Please - as my 90 year old mother once shouted at me when I was getting myself in a state in the same workplace hell-hole - NO JOB IS WORTH MAKING YOURSELF ILL! If you are really wretched - just don't go to work until you feel better. Really - stay at home. Go and see your doctor instead. And use the time to look for something else, or part time. No-one has any duty to make themselves ill for a job, or expect anyone else to, and frankly, it is crackers to think otherwise. Believe me, the moment the school had no further need of you and they legally could get rid of you, you would be out, no matter how committed you are to the children and that teaching is a vocation blah, etc. - and quite right as a use of public funds, too. So keep that in mind. When the chips are down, it is actually just a job - hours of work and skill you have contracted to sell. If you are ill you don't go to work - that's in the contract.
Sometimes you can't do a job, etc, - you actually can't go on, no matter how worried you are about what will happen if you don't. Amazingly things usually turn out OK for people - yes, you get frightened and you feel that the worst has happened, but then you find something else, you adjust, something turns up and you realise that actually you have just been banging your head against a wall for a very long time and it is nice when you stop. Easy to say, I know, - but largely true nonetheless.
Having retired now, I do not wish I had spent more time marking or preparing lessons. I do not miss my very high flying jobs at all. In fact I very rarely think about work at all and I have not the slightest doubt that the people and students I worked with very rarely think about me, no matter how much we liked each other. We are not irreplaceable and one day we all get dispensed with anyway. I have less money and I manage on it and am more than happy. I hope you can be too.