So DONE! Crazy, rude demented parent

So, my mother-in-law was physically and emotionally abusive to my husband and stole piggybank money, candy when he was a child. This is nothing new.  This isn't 'the disease talking', this is 100% her, contrary to what her distant siblings try to say.

We moved in because hubby was seriously ill in 2015 and I needed 'free rent' while I got him better. Surgeries, specialist, meds, things I had to pay for out-of-pocket because insurance wouldn't cover was involved, and he wasn't well enough to tell me why moving in with her was a bad idea. Things were fine for a few years, esp after he recovered. The whole time, I've cooked because she doesn't know how to, cleaned because she won't, helped her clean up after her incontinent accidents. We've taken over multiple bills like electric and misc other utilities, pay for all of the food and gasoline, buy any rx she asks us to, pay the mortgage for her more than twice a year but less than half the time, odds and ends as we can. I take her out to eat, have trees leaning on the house removed by an arborist, buy her clothes, whatever is needed that we can afford.

She learned that no one wanted to put up with her awful behavior, fixed it a bit after her ex-husband and kids each ran from her her, but is declining into old ways now. She has frontotemporal dementia, as has become clear in the past few years. She fights getting a dx, refuses to take meds.  She falls for scams and loses her social security check monthly, hasn't paid the mortgage on time since 2019, hasn't paid the mortgage at all since March 2020.  Oh, and she hid a cancer dx that's metastasizing.

Problems: She won't listen to us about the scams. She will lose her home due to this. I can't afford to pay for everything for everyone, so I am not paying the mortgage. One of her sisters is reviewing her finances, has POA, but can't stop it from happening. She's verbally abusive, and I can't get her prescribed anti-anxiety and agitation meds or get her to take meds that would help it. She hits my kids for rubbish reasons, even when I am standing beside her. The kids are not allowed alone with her to try to prevent this, but she'd rather hit them than say a word to their parents. Now the children aren't allowed within arm's length of her. She steals clothes and sheets from me to cover for her pooping on herself all day and night. I don't mind buying her clothes, depends, or new bedding- and I pay for it all- and I don't mind cleaning it all but she won't admit she has a problem and would rather steal and lie. All of my bottom sheets are gone and she viciously says the bedding is all hers. She steals from our purses, wallets, piggybanks to fund her addictions. The money she steals includes gas and grocery money. She steals medicine and drops pills on the ground where my infant finds them- and this has happened multiple times. She jacks the heater up at night until we are all sweating and can't sleep, but refuses to put a blanket, robe, or socks on herself. I closed the vents to our bedrooms, bathroom, kitchen and opened them wide in her room, so her room is nice and warm. I pay for the electricity and I don't like having to open windows and doors to vent heat. I can't afford it. I'm turning the electric furnace fuse off before bed each night to stop this. She has convinced several of her out-of-state siblings, who will not visit to see what's going on, that we are financially exploiting her. This is a minor complaint, as I have provided evidence to the lead two siblings that proves otherwise and invite all takers to come see.

Does anyone have any advice on coping with this trash? I'm already on therapy and meds so I don't snap and murder her. We can afford to leave, but it would be tight or my husband may have to find a job. She would probably be dead in a month if we left. She can't afford care and won't let a doctor set her up with care. Can I get a social worker to visit to give me advice? No one is picking up the phones right now!