Bitten: Number 1 in series (Women of the Otherworld)

I've been fighting it all night. I'm going to lose ... Nature wins out. It always does.'
Elena Michaels didn't know that her lover Clay was a werewolf until he bit her, changing her life forever. Betrayed and furious, she cannot accept her transformation, and wants nothing to do with her Pack - a charismatic group of fellow werewolves who say they want to help.
When a series of brutal murders threatens the Pack - and Clay - Elena is forced to make an impossible choice. Abandon the only people who truly understand her new nature, or help them to save the lover who ruined her life, and who still wants her back at any cost.