Observeteen-having dealt with these problems myself numerous times being in kiruv krovim and having had to steer at least 10 girls away from bad boy friends, I’ll tell you that you were def right to talk to her. She trusts you, and is tellling this to you for a reaction. that is a. Be calm with her, build up her self esteem, and my advice is to tell her to listen to Rabbi Wallersteins shiur on Torahanytime.com called the magic touch. It is unbelievably powerful. Maybe just suggest it and let her toy with the idea.
13 is a scary age for someone to be used already. Good for you that you are oding something about it.