START A "PAPER TRAIL"
If you know your boss's email address I'd send an email, that way it's in writing and date stamped. I'd let your boss know what's going on and also tell your boss that if he/she had the b@lls to actually be a boss and not a friend you wouldn't have to play the "boss". Naturally, how you word that will play a huge part in how it's taken. Don't say it as I did.
They say that the squeeky wheel gets the grease but sometimes the squeeky wheel gets replaced. It's better to leave on your terms and not theirs. I say this b/c all too often someone will complain and they are retaliated (sp?) against. CYA!