My mom's friend created a chaos and absolute turmoil into our family. When we moved to NJ awhile back she hit on my dad and introduced him to a woman who became my dad's mistress for a few years (My dad was happily married to my mom for 32 years). In addition, she humiliated my mom in so many ways yet my mom never cut ties with her (since she believes in being amicable with literally everyone). As if what she did to my dad and my mom weren't enough, she even gave me problems too. She gave me a bad reputation and made me suffer in many ways. I don't understand why my parents didn't (and still won't) cut ties with her or at least pay back for what she did to us.
Sometimes parents don't want the drama for the sake of a peaceful life. This woman sounds toxic but instead of seeking revenge, you should confront her on your parents behalf, speak your mind on the situation then cut all ties. Life is too short to deal with such nasty people.