No, but I understand your frustration. My oldest daughter went back to her husband a few months after he beat her up. I was actually shocked because I always looked at her as a strong woman and smarter than that.
I know there is a difference between a daughter and a sister, but my advice to you would be to step back, but let her know that you still, and always will love her. As much as you might want to, don't read her the riot act or argue with her about it. Someday, she may decide to really leave the guy (my daughter finally has), and she will need to know she can talk to you and won't be afraid you will start in with the "I told you so."
Hugs to you.