What do you do when your mom has dementia, is accusing you of theft, and has a cousin helping her make accusations instead of helping her?

I have been helping my mother on and off for 8 years. Even before her mind began to slip she was extremely abusive, so much so, she has no friends, and her last friend who committed suicide left a letter saying she would die alone. My mother has been taking Pain meds and Xanax for 20-30 years. Each month she runs out, goes through withdrawals, and repeats the cycle. Anyone who has tried to help has been accused of theft and all sorts of things. Over the last two years during Covid, I went to help her, and it was very hard on me as she is extremely well off and my girlfriend and I are just making it by. While there, my mother would hand me her card, and say go buy groceries and medical marijuana, (she would eat 1000mg) in one sitting. She is extremely judgemental, and I believe has always had an undiagnosed narcissistic personality disorder. She never asks anyone how they are. Has no interest in others, and always plays the victim. It's always someone else's fault. After months of abuse I had to leave, she literally would make me suicidal. She helped us pay for rent while taking care of her and used that as a way to belittle us. On top of that, she also is showing signs of dementia. But what is worse, is she has filed accusations against me with the police and claims I stole her money. This is common, she has done this for EVERYONE who has ever dealt with her. But I'm the first she's actually called the police on. Well, actually it was her older cousin who is doing all the writing. I'm afraid. Because I lack the funds to fight her, she's a millionaire and I live from gig to gig. She married into money - she did not earn it. But I still check to make sure she's paying her bills, and her house is being maintained, as I was helping while there, so most of the people who were fixing her house, know me as the point of contact. She has claimed I pointed a gun at her, stole 250k, and used her account without permission (she was so high most of the time) and now she is telling people "I kept her high". The problem is she is the actual person who took the 250k and lost it. The wells investigator told me she exhibited signs of dementia. She rarely takes showers. Never leaves the couch. And always complains about the money she didn't get when her husband died - because while she was suing her ex's husband's family, she pulled out in front of a guy driving a motorcycle who died from the accident while driving under the influence of pills. She managed to squeak by with involuntary manslaughter but it made me have to help her sign a settlement because we were dealing with two cases at the same time. Within the last 6 months, I left, changed my number, and cut contact with both her and my cousin, who enables her, but has never actually come to help her. Even after all of this, I was trying to protect her from herself, because I think she has mental problems. But now it's pretty bad because she and the cousin are twisting everything into something that is not true. She literally tells anybody and everybody I abused her. But the truth is she and her alcoholic husband abused me since I was 10. Verbally. Emotionally. I used to call her house Azkaban, to keep it light. There are times when she could be nice. But then she'd suddenly change and become vindictive. I think she may be one of the meanest people I have ever met. And obviously, I'm not the only one. Today, while checking on an email I received from waste management, I was told the manager someone was living downstairs, and then called three times asking if she paid the same bill within a 24 hour period by the manager. I don't know what to do. I feel helpless and have no way to protect myself, and it seems no one believes me about her condition. Even the protective services investigator said the police told her "it's not illegal to be crazy". I am really close to getting my life back on track now. But knowing she's trying to have me arrested is stressing me out. What can I do?