Why is everything blamed on me?

Basically my "friend"( friend a ) just go in a whole heap of trouble at school and he's blaming it all on me. Heres the story a couple of months back he asked me for a friends email address i gave the address then suddenly he's hacked into this friends ( friend b) facebook account and posted bad stuff then another friend (friend c) took evidence of this and showed it to friend b who showed the teachers and now because this isn't the first time friend A has cyberbullied he got into aheap of trouble maybe even expelled and he's blaming it all on me i explained saying you asked me for the email i didn't tell friend c i didn't give him evidence it was friend b but he doesn't belive it and he's all like " cool good for you", "Bye" " I don't give a **** it's all your fault" any ideas?