I doubt I can be helpful. But if it were me in your position, I would see caring for my mother, with all that hurt and bitterness in my past, as a penance for my sins. I'm not Catholic so I don't have any experience with religious confession. I'd also stop talking to Satan. For me, this would still be difficult to bear, but I'd see some purpose in it that serves me as well as my mother, and the best I could do for her, beyond what's basic, would be like extra credit.

But seriously, please stop talking to Satan. I believe evil does exist, but probably it's best to avoid engaging with it. I wish you good luck.