You will need to fight back, grab your life back, OP.
My dad is 87 and in good health. I stood by him, did errands and admin, saw him two hours almost every day.
Then, at the end of July, he decided he never wanted to see me again, and said a final 'goodbye'.
Come mid September, he needs my help with an admin task, so he's back. But I'm not giving him two hours of my day. I got my life back, his choice, and I'm not throwing it away again.
Your mum is only a couple of years older than me. I don't know her mental or physical condition, but most people our age can manage, after a fashion.
Ultimately, if you were 'dead to her', you'd be alive to you.