Has anyone ever walked away from it all?

I care for both mom and dad for nearly 8 years now. Cancer, dementia, heart, blind, half deaf. I did work full time for 6.5 of those years. I do all the financial, legal, medical, day to day care. Dad has helped a lot for about 2 years, before that his involvement was chauffeur only. For the first 3 years eventhough he was at the appts. he didn't even know what kind of cancer mom had. It was touch and go for a long time. They called me day and night, still do. I live 1/2hour away. My sister lives 1 hour drive away and though she has the financial means and know how (LVN
) she is not involved save to forbid anyone in the family to help or even call and create chaos with outrageous lies. My dad doesn't have dementia but has done very little to correct those lies. I have exhausted all my life's savings, got fired from my job in large part because of the constant calls, drain, stress. I have cashed in all my 401k to keep us afloat for 7 years. I told them Christmas that I would be out of money in a just a few months. Nothing was done. My sister tells everyone she gives 500 a week and that I steal from them! Dad finally after years of this spoke up, but after so many years, so many lies no one believes anymore. I survive barely yet dad still wants me to pay for meds, go to each and every appt for him and mom, go to their house 5-6 times a week, manage meds, take care of bills, taxes, insurance, clean, buy groceries, calm mom down, be on call 24/7 365. Since no one stepped up I got a small job basically being a maid 12 hours a week and he went ballistic,cussing, fussing, throwing things. He wants me to not work those 12 hours and survive off the $100 he gives me a month. Even today, the only day off I wanted this week, he calls, he broke down at the gas station. I said I am on my way. It is a half hour drive there through traffic. He calls 20 minutes in, where am I? How much longer? I am 2 minutes away after going on freeway 80 miles an hour, swerving in and out, because I know him. My sister is a prosperity gospel adherent. Says God hates us because they are sick and I am now poor. If we had faith we would be healthy and rich like her. Her words. We tried to sell property that is down the road from her. She blocks it, tears the signs down, stops and tells prospective buyers the pond is poisoned and will take at least 10k to fix. I wanted to sell to pay bills and get them on Medicaid. She has presented them with documents to sign everything over to her and her eldest son who is just like her. Dad wants to leave a little to each of her kids, two of the four she has disowned. She says she deserves it all. Through name it and claim it, gospel of greed only she is worthy and all the lying, coercion and suffering she is causing is ok. God has "favored" her so its not really a sin. I lived decades of my life away from them, happily, peacefully, drama free. Even though she is the eldest I felt it my duty to come and help my parents when they became ill. My parents raised her children and supported her in so many ways. The reason she is where she is is because of them. But money talks.
Today mom had a bad headache, they asked me what to do as we worry she is having another stroke. I saId hey, I have told you so many times, why dont you call the nurse?You dont want to bother her at work, though you called me constantly, well it Sunday, ask her. Dad spoke to her for 2 minutes, she said its probably nothing and went on to quiz him about what I was doing, was I still working, how often, blah, blah. Even though I have begged Dad not to give her any information as she twists and uses it in her fabrications, one grain of truth with a heaping pile of lies and it creates doubt. Yet dad sat there and answered every question. She didnt even tell dad what to give mom for her pain. My niece, one of the disowned and her husband whom dad absolutely loves have both told him not to give her info. Yet he still does. When he hung up I laid into him. Told him what I thought. Told him I want to never see him again. Told him that even though he likes to say this is my responsibility that he is the husband, I am helping him not the other way around. That after destroying my life for them and he's not worried or even thankful that I am done. That he is a selfish, weak human being who takes his trucks to the shop for the slightest squeak yet he knows my check engine light has been on for over a year, that one tire has a slow leak that I keep airing up and that I have not had working plumbing or working locks in my house for months. Yet he brags on his millionaire eldest daughter. If I walk away hensays he will kill himself, ever manipulating like my sis. Adult protective services said they cant get my sister for neglect because I am helping. They said this is the worst case they have seen in years. That is nothing to be proud of I know. So, walk away? Let the chips fall where they may or let them suck the last bit of blood out of me?