My 88yrold father was recently diagnosed with Lewy body dementia moderate stage.All new to us.my mother have her own health issues also.i care for both of them but they only want me 24/7My mother is so selfish and gives me a hard time and says some nasty things to me I had numerous fights and walk outs but she rings crying and apologise we can't cope with out you.I'm smothering and my own health is been effected.My mother said to my son she can have a life when we're dead.She throws at me all the time that she minded her mother while she was raring us as children and I'm expected to do the same with her.I can't cope anymore.
The reason APS is a solution if your parents don't have PoAs is that you won't be able to pay their bills, have discussions with their doctors, make decisions on their behalf. And, your parents are refusing outside help and you are already overwhelmed and on your way to burnout.
Your Mom sounds like she is in moderate dementia as well. If I were you I'd decide to move out, then I'd call my siblings and explain the situation so they aren't shocked when it happens and so they can step up if they choose to until there's a permanent solution. Even if your siblings are enraged and refuse to help, you must leave and call APS. The longer you wait, the longer you keep propping them up, the longer a time it takes for a solution to happen.
I'm so sorry, you're not imagining this is a bad situation. But you're going to have to do a hard thing, but then things will improve for everyone.