Ex best friend of 12 years

My ex best friend has completely changing and is being awful to everyone and has completely changed. I wan to confront her about these things and give her a piece of my mind but she knows way to many personal things about me and my family so i can’t liss her off or she’ll tell her new birch ass friends (I just figured out she’s capable of doing this, I used to think she was nice but irl shes a conniving fake bitch)

Ik I’ll regret not confronting her tho and it’s driving me crazy! What should I do??