My brother told me taking care of Mom is my job because I am the daughter. Any advice?

I have for 33 years, and I am exhausted. Mom seems to excuse him.Brother and family live within 25 miles of Mom, I live 10. They only show up when they get family dinner or a holiday. She had a tree smash her hose when she was 90, they never came to see, let alone help. I did it all, cleaning out her stuff and moving it to storage while the house was repaired, and returning it all when it was done. She was in the hospital 3 times that summer, had a biopsy the last time, and after 3 weeks NONE of them had inquired about the outcome! I can't get my head around that attitude. When Mom is gone, I never want to see them again. I know that is not Christian, but I don't think they are very Christian either. Mom has dementia, lives in her house, which means 24/7 for me. She is the most stubborn person I have ever known. She thinks she never misplaces things, her TVs are junk - she can't remember how to use the remote., etc,etc. I'm 70. I have lost the last 5 years of my life. I love her and don't regret it - yet. but the feeling of helplessness is getting overwhelming. Any suggestions. We have an agency in 1 day a week, which Mom says she doesn't need. She does nothing herself anymore, just flits around the house and moves things. .