I'm going to expose my friend for cheating
What is your reason for wanting to have her exposed for cheating?
She's always finding excuses to cheat me.
I understand, but it's terrible to rat out your friend if it'll destroy your friendship. You should have a talk with her about this first.
Nah, I want to see her bow down her head and feel bad about it.
You should allow your friend to have the honor of fessing up to their own mistake. You telling on them takes this opportunity away from them, and then not only did they cheat but they also did not have the chance to own up to it.