Hi Canoe and welcome to our online community

Your mother's behavior sounds very difficult indeed, I can see how this would take a toll on you. You mention your two siblings, how is your relationship with them?
Last year, when she began to demonstrate increased behaviors associated with BPD, she made some very serious allegations that were investigated and and shown to be false and unsubstantiated.
Did anything happen last year that preceded or coincided with the increase in her BPD behaviors?
Dealing with false allegations is never pleasant. Even if the investigation showed them to be false and unsubstantiated, that whole process is often also unpleasant and potentially damaging. Against who did she make those allegations?
I struggle with the possibility of removing her from my life completely because she is so abusive, but then I feel guilty because I know she is mentally ill.
She might be mentally ill, but being subjected to abuse isn't healthy and can really take it's toll on you. Your own well-being matters too and I think it's only natural that you would consider taking steps to protect yourself from her abuse. No matter the level of contact you have with her, having firm boundaries in place will be crucial. Have you ever set and enforced boundaries with your mother before?
Take care
The Board Parrot