I'm so sorry you are going through this. The best gift my parents gave my sisters and me was to move to a retirement community with stepped care. My parents had cared for my grandparents at home and never wanted us to have to do that. My mother ended up in the nursing home after a severe stroke and my father went to memory care. It was a great relief not to worry about him wandering away and getting lost, like the time we got a call from a stranger 100 miles from his home to come get him. (He was still driving.) Do not fight memory care. She needs it. You may not like your mother, but I don't think you want her hurt or killed because she didn't happen to run into a kind stranger.
As for your anger and resentment, it's perfectly natural to feel that way. My husband and I took in my mother-in-law and we cared for her until she died. She was a mixed bag and bipolar to boot. When she was bad, she was horrid. I used Ancestry to assist in my calculation. I added up the ages at which her parents, grandparents, and great-grandparents died and came up with an average that gave me a great deal of comfort because it was only two years away. Amazingly, it was the exact age she died.
See if you can find another caregiver to commiserate with. My friend Debbie and I were able to vent to each other because she was caring for her husband's seemingly immortal great aunt at the same time. Ordinary people are horrified when you talk about calculating death dates. Other caregivers totally get it. Hang in there. Everyone dies eventually.