God help you OP.
You have never had a moments peace from this woman.
She is like your tormentor your whole life.
Everything is about her.
Whatever is going on with her, by gum you have really suffered.
You have MY full sympathy.
I would tell whomever that your father is safer in the care home than with her.
I would take a deep breath and try and realise that YOUR children and family are YOUR priority.
You need to protect your MH and general health as your priority.
Who will look after your children if this woman drives you to a complete breakdown?
So you have to find the strength and energy for boundaries.
Stop taking ANY calls between 8pm-8am.
Stop taking them in work.
Talk to your sister about approaching her GP, preferably an email, with your concerns.
Your mothers whole life is about her and her feelings, you cannot change that, its too late.
However, you can start protecting yourself.
Get onto adult services and report her behaviour too and flag her too them.
The most important thing is to step away before YOUR health becomes impaired.
I think you should suggest the care home staff call social services to help your mother.
You cannot and should not take this on.
You have tolerated her behaviour for too long.
Time for you to protect yourself IMO.
I apologise if that is harsh to read but giving up your health, when your children need you is not the right call here.
You need to protect yourself from her.
Wishing you well.