Don't talk to her about that. It will just be a VERY uncomfortable convo.
Regardless of why she did PICS, it really isn't anyone's business. I know I wouldn't look at the same way at the girl for a while after I found out her secret though.
But that's not something you throw in their face when you get into an argument either, because she could have done it to pay some bills, then she would feel like sh!t, everyone would avoid her after the secret came out, then she would have to move far away and later you would find out she is doing it full-time.
I know, crazy scenario, but I thought in putting out there. Don't throw it on her face if you guys ever fight