Inappropriate use of digital media

A few years ago at our school there was a private group on facebook that would post mean, derogatory, and false rumors about others in the school.  It was a group of upperclassman and how word got out was that some of the members turned on each other.  The school ended up finding out about it and contacted parents and the site was taken down.  The social media bullying is becoming the main source of bullying in our schools and most parents are not aware of this.  

I find that many parents are either ignorant or oblivious to what their children do on social media.   Should we educate them too?   Newsletters?  Info at Parent - Teacher conferences?

Parents never, or almost never believe that their child would be cruel to someone else.  that is the hardest part of our job.  Getting parental and administrative support.