Emotionally abusive mother and I'm the only child-what to do??

My mother is 94 and I'm 56 years old. I'm an only child. My father died 30 years ago and the rest of our extended family, what little there is, is either dead or on the other side of the continent. My mother has been verbally and emotionally abusive to me since my earliest memory, and her treatment has become much worse with age.

I'm pretty certain she has dementia. She cannot keep track of her money and checking account and mails checks for bills and taxes multiple times and overdraws her account each month. She let me be added as a joint account holder so I could monitor the balances, and now she calls me 20 times a day because she can't remember the balance each time I tell her. She lives alone, refuses to sell her house and move in with my husband and I, or to assisted living. She refuses to see a doctor. She leaves food in her oven, remembers to set a timer, but forgets about it and sets her oven on fire. She cannot remember what day it is or what she got in her mail. She has misplaced boxes of blank checks and forgets to feed her pet poodle. She cannot operate her TV remote or a cell phone. She no longer answers her home phone. Every day she needs something new from the grocery store. A few weeks ago I bought her three boxes of Minute Rice, at her request, and she lost all of them within 24 hours. She's rail-thin, but her cupboards are full of food (not the rice...have no idea where all that rice went...)

I live 25 minutes away and was very sick with COVID until 2 weeks ago. My mother was enraged that I was contagious and too ill to see her or take her to the store. She doesn't understand why she has to wear a mask and had no understanding of how sick I was. All she could talk about was her checking account balance, the missing rice, her poodle needing a trim, and how I letting her down by not being there for her every day.

I don't do anything right for her. I married the wrong man (twice), my daughter in college is selfish because she doesn't see her Nana every weekend and has "changed". I am, in her words "crazy and worthless" and "a burden." I have been called crazy, stupid, worthless, a burden and, most biting, the "one who should have died" while my little sister, who died in infancy, should have lived. She wishes I had been the one to have been born prematurely and die instead of my baby sister. She also won't believe that my father sexually molested me and says it's part of my craziness. This is NOT recent behavior. I have been hearing these words since I was a child. But things have become unbearable the past two years, and now when I am with her or on the phone with her, all I hear is how awful I am.

Two months ago, I had a complete nervous breakdown and was diagnosed with PTSD, in part from my mother's continued treatment. I have never been able to hold down a job and my husband expects a "contribution" since I don't work, so Mom has always helped me out-at a price. She says she has the right to treat me like crap, and I have to put up with it, because she helps me financially. I was on SSI for awhile but my dh got a small raise so now I no longer qualify. So dh wants a "contribution" and Mom was always happy to do it if she could continue to belittle me. So I finally had a psychotic break 8 weeks ago.

I have a worthless POA she signed 30 years ago, leaving me in charge of everything financially. I cannot begin to figure out what to do, how to handle her money, or her. My husband has been running interference for me, trying to take care of Mom, while I'm trying to see psychiatrists and psychologists and find meds that make life bearable. I'm at my wits end and feel hopeless, weak and tired. I haven't spoken to Mom in a week. My doctors tell me she's toxic and I need to make a clean break, but how can I leave a 94 yr old woman alone? ? And advice appreciated, thank you.