My Alpha Mate is Fated to My Sister

Mari is running away from her abusive boyfriend when she runs into Stefan. Stefan, a werewolf king, has mistaken her for his destined mate. Before she can correct him, he bites and mates with her. Mari is happy with her newfound life as the werewolf king's mate, but will her happiness last when Stefan's fated mate, who so happens to be her long-lost twin sister, shows up?