Yolo I understand.
About four years ago, when I was alread six or seven years into the elderly parents thing, with unhelpful sibling, a big mother crisis after a fall, her continued agression towards me, lots of issues managing her financial affairs, and the standard supporting teenager stuff, we had an awful summer which involved DD being helicopter evacuated to hospital whilst on holiday and DH ending up in intensive care.
A couple of months later I sort of ran away. I was down visiting my mother and checked into a cheap off season hotel and did very little. I walked, read, and treated myself to some nice meals. And no demands. I renewed my hotel room on a daily basis, for about four days until DD phoned to say she was missing me and could I come home.
Since then it has been easier. Their needs have reduced, though DD had a bumpy first year at University, and I have got more able to claim my space. I have become a bit of a lady who lunches as I consolidate my friendship network. Plus my spare time, spare till my mothers next crisis, is being used to catch up on theatre, evening classes, walking etc.
Its sort of why I went missing from this thread. You can only support effectively for so long. It very much sounds as if you need a break. Explain yourself and your needs to your family. It is actually important that your children do not see you as everyones doormat.Take a few days off when you can. Is there an old school friend you can visit? Or similar. Something absolutely non demanding and fun. And anyway you can outsource the domestic chores. Children cooking one day a week, supermarket deliveries, cleaner? I definitely felt I needed to re-find myself after the parenting years.