I've just read this whole thing and it is the most saddest but frustrating thing I've ever read.
You say she is having you jump through hoops and you oblige... but do you not realise she keeps moving the goal posts! And you keep on obliging.
She knows this is nuts and so do you. You are very trauma bonded to this woman. Maybe look up stockhold syndrome as she has such a hold over you...
I really think you need therapy by yourself by a trauma specialist. It can take people several times to leave their abusers but you have to really understand right now, at what she is doing to you.
How many more years do you have on this earth and do you want to stay in her prison? It's also self imposed to a degree because you won't leave her. She will survive fine without you, just watch. She uses her needs as a way to keep you there do you not see? She will survive with carers just fine.
It's time you freed yourself from this nightmare. What are you modelling to your children? Grown or not, this must be awful for them to witness.
Life does not have to be like this. You can be on your own for the rest of your life or meet someone who will not treat you like this, once you are on the way to healing.
I used to when addicted to smoking, when I thought about giving it up, how will I ever cope with it. And that frightened me that thought. I was 100% addicted. Glib example I know but you are addicted too, to the highs and lows. Your cortisol must be in bits. Don't you crave peace, breathing room and your own space?
You must keep coming back to this thread for a reason. I think you want to get out but you are glued to the spot. Make this year that his happens. You can do it. She has zero loyalty to you. Don't waste another precious minute on her. You can do this, be strong!