This terrifies me, my mom is getting older (60s) and is starting to become more forgetful and reliant on writing down notes to remember things. Not anything near as bad as what you're going through, but I worry that it could be early onset dementia. Even if you had power of attorney, mk brings up a salient point about their perspective. Dementia and Alzheimer's are among the worst.
I once heard a doctor give a great explanation of the difference between getting old and having dementia: Getting old is forgetting where your keys are. Dementia is forgetting what your keys do. My mother is 79 btw so hopefully you have a decade or 2 to go. And Power of Attorney. Oh my gosh. Yes when she fell down the stairs and was in the hospital for a broken arm she agreed to that. But as soon as she got out there was no way as as I/we were trying to "control" her and so things are looking pretty shitty and complicated.