What should I do when "friends" are being dumb?

I'm no longer friends with them anymore (obviously) but these three girls have decided to make up a rumor that they have several dirty pictures of me that I sent to this guy that I hung out with. Fact is, I never sent him any dirty pictures, but this guy is one of the girl's ex, so they're pissed that I hung out with him even once. They've all been verbally abusive and harassed me, and I have texts to prove this. They've called me many names, and called me "stupid, dumb" and said many demeaning things.

If I could, I'd go to my parents, or the police, and tell them what's up, and get the girls in trouble for this. I'd have no problem being a narc if they got what they deserved. But, the girls know I smoked weed, and so they would go straight back to my parents and tell them this. At this point, I still wouldn't pass a drug test, so I can't do this yet. What do I do?