Hi TBH.
I am so, so sorry. When I read your post I could feel your despair. You are like a long distance runner who has used up all her body's strength and nutrients and is still pushing herself to reach the finish line, but it keeps moving further away. Dear TBH, you have to stop and take care of yourself. Urgently!
I remember a story an old lady told me once. As a child she had lived through the Great Depression. She told me that some days there was barely enough food for one person. When that happened, the father got the food. Why? Because he was the breadwinner. If he went down, the whole family would be lost.
It seems to me that you are in a similar situation. If you go down, there will be no-one to support your husband. So remember that you are now the most important person for your household, and seek/demand the support you need to continue to carry on. It sounds like some respite care would be good, to give you a break. And home help would no doubt be useful. But I can only give my personal opinion, you need to reach out to the people and organisations that provide the services. And quickly!
Finally, about the oblivious and tactless doctor. Speak up, TBH. Remember who you are and the Everest you climb every day. If it was me, I think I would look at him in the eye and say "I was busy having my daily massage and manicure". But you must think of your own response - one that can be said politely but packs a bit of punch. Make him (and his ilk) SEE you.
Finally, I am reminded of the instructions that we are given when we are on a plane that is about to take off. In an emergency, a parent must first secure their own oxygen mask. Only then should they attend to masking their child or children. The same logic applies to a carer and care recipient. Please get your own oxygen supply set up, TBH. It's urgent.
Cheers,
Little-fish