If I may make a suggestion about you talking with the parents. Make sure the kids aren't involved. More or less make them aware of the situation so they can take action and make it clear that telling who tattled will only make things worse. I was one of the bullied in school and anytime my Mom talked to the other kids' parents they always told who told on them. So they just made it worse later.

__________________
"BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Will he offer me his mouth? BOY: Yes. GIRL: Will he offer me his teeth? BOY: Yes. GIRL: Will he offer me his jaws? BOY: Yes. GIRL: Will he offer me his hunger? BOY: Yes. GIRL: Again, will he offer me his hunger? BOY: Yes! GIRL: Yes. BOY: On a hot summer night, would you offer your throat to the wolf with the red roses? GIRL: Yes. BOY: I bet you say that to all the boys!" -Meatloaf