What She Means to Sky

Sky is madly in love with his best friend.
no, she does not know. And, no he hasn't told her yet.
But when his world is crashing down around him he realized he must tell her the truth, or risk losing her forever. He has to tell her everything.
He is a werewolf. And not just any regular, run-of-the-mill werewolf, a giant one. As the population of the enemy increases so does their size.
How can we explain his sudden growth to her without scaring her.
Can he do it before he dies?
(7-11-14: I'm having trouble with the cover at the moment but it will be fixed soon.)