I say talk to the INFJ first. He probably didn't intend to hurt your friend (INFJs seldom do), and he probably doesn't realize she is hurt. If he's anything like the other INFJs here, he'll be more than happy to reconcile with her.
HOWEVER, if you proceed to hurt him, expect him to be just as happy to pay you both back with interest. NEVER underestimate an INFJ's lust for vengeance; "it hurts me more than it does you" has no meaning to a hot-headed INFJ.