Aces Down by Denise Golinowski

Solitary witch Norah Cartwright settled in Colorado's silver country, seeking protection from vengeful werewolves and a place to rebuild her life. When former boyfriend, Tristan Byrnes, shows up at her bar, Aces Down, it seems there's not enough silver in them hills after all. At least, not for a werewolf determined to win back his mate. Instead of flowers, Tristan brings irrefutable proof the pack has been called off her trail, but he never guessed his proof was more time-bomb than peace-offering. When her past blows up in her face, is Norah strong enough to trust Tristan and defeat an attack from beyond the grave?