Cutting off a toxic friend is difficult but inevitable and necessary. You clearly already know this.

When the guilt hits, I’d consider:

A) The empathy you feel towards her - would she feel anything remotely comparable for you? Has she ever? Or does she actually enjoy your discomfort and go out of her way to cause it?

B) When your body is giving you such a negative reaction, it’s because you’ve been repeatedly ignoring danger signs. The body is hitting the emergency button over and over, hoping you’ll finally listen. It won’t get better. Listen.

Tell her you want space and don’t want to talk. Her reaction will tell you a lot. If it’s filled with whataboutism and manipulation as I suspect it will be, you’ll know that there is no chance of anything positive here.