I agree with everyone here that posted above. If you ever do have to interact with her, practice Grey rock. Meaning, when she tries to get a rise out of you to get her narcissistic supply, give her basic answers, don't respond to her words because narcs love that. Then leave the conversation or the room as soon as you can. She will quickly get bored and move onto her next target. The best way is to go no contact though.

When and if you practice Grey rock and/or go no contact with the narc, you may encounter a smear campaign by the narc and their flying monkeys. Flying monkeys are people that they enlist to enact their abuse. It really is horrible and I lost basically my entire dad's side of the family due to a narc family member. I am still healing but I am much happier. Be kind to yourself, and if you don't have a therapist it would be wise to look into one that specializes in trauma. Narcissistic abuse is insidious and literally poisons the family and related relationships. I'm sorry this happened to you.

Look up Kris Godinez on YouTube, it really helped me.