need help!

I have a friend who can be a cock sucker at times. When I went to bathroom he grabed my phone , texted the most sick and disgusting looking girl at my school saying "will you go out with me". The worst part is that she said yes and sent nude pictures(that i deleted)to my phone. The girl told everyone of my friends that we were going out.

HOW CAN I GET BACK AT THIS MOUTHER FUCKER FOR STARTING THIIS SHIT!?