You have my sympathy and best wishes. My sister was initially supportive when my mother was hospitalised last year before being moved to a care home. But when it seemed, briefly, as if Mum might have to be moved on, owing to aggression, my sister's way of reacting to the stress was to attack me verbally in a savage and unprovoked way. It was a terrible shock to me.
I think it's good advice given above to make sure that all financial dealings are recorded and that anyone making accusations against you can be shown 'not to have a leg to stand on'. Also, it's best to get the sympathy of any caring agencies involved - or even ask advice from Age Concern or others.
Then you need to think what the best way is for you to handle the interpersonal stress. In my own case, I was able to avoid an absolute breach and have kept things distant and polite. It's been extremely hurtful but the wound is just beginning to skin over. I know that if I'd attacked my sister in turn, or let her cut off all relations with me, my pain would have been even greater.
But some people advocate firmly stating one's point of view before severing links.
Take the course of action that causes you least stress. You are the one who counts here. You have been strong for your mother and you do not deserve to be attacked or hindered.
Very best wishes