Yowza, I know what it's like caring for a "wicked mother" at her worst. I used to drive to work and fantasize about continuing on down the highway and never looking back.

The only problem was I was a 30 year old mother myself and too many people needed me.
I don't know the details of your situation, but I think this would be a good time to ask for help. It would be nice if you could arrange for a little time away with friends or doing something you enjoy. I always found it helpful to step out of the box for a little while because it gave me the stamina I needed to keep up my hectic schedule. It also provided a greater appreciation for the gift of life - even if it's in a box.
I'll keep you in my prayers.