Ignore her email and continue onward as you have been. She made her bed and she can sleep in it herself. you stated that many people are mad at her and that underscores my previous statement. She has to face her own monsters in the form of her behavior that intrudes on other people's boundaries.

You are not obligated in any way to respond, nor do you need to do anything for her. You did what you could by befriending her in the first place, and she has been a thorn in your side because of her lack of boundaries. Don't let her make you feel guilty you are not the one that has broken the friendship.