I feel for you op my OG mom died from cancer when I was like 10 I distanced myself mentally, and didn't really understand the situation too much. On your situation it's her time to pass on to the next life. I'd be appreciative of the time you have to achieve closer. Time to speak your last...
My Great grandmother has dementia, she always think I steal the most ridiculous things, but some how I am her favorite, and I try to take care of her when im there. Rip to your mom and may she rest till she awakes in a better place