I'm going to break up a friendship my girlfriend has.
What makes you want to do this?
She blamed me for something I didn't do.
It's bad that person did that, but you shouldn't interfere with your girlfriend's friendships. You should be honest with her about what happened.
We are not talking about this.
It is better to tell them the truth about how you feel instead of ruin their relationship. You never know if it might backfire and she could choose them over you.