My sister's behavior is problematic and I'm going to cut her out of my life.
What about your sister's behavior is so problematic that it's causing you to cut her from your life?
I've tried to talk to her about her behavior on many occasions but she won't make any changes.
It's okay to set boundaries with your family. You should communicated firmly with your sister that you don't want further contact. If not, she might continue to try and reconcile.
I told her not to contact me again.
Sometimes we can't work out our family differences and we have to cut ties with them. If you know if your heart that you can't overcome your differences then it's best not to have contact with them.