Vengeful King by Mary E. Twomey

Retirement isn’t all it’s cracked up to be, especially when the world begins falling apart the moment you step away.
King Ronin doesn’t know what to do with himself after handing the throne down. After one of his parties takes a deadly turn, he realizes his role in leading the territory might not be over yet.
With a mysterious poison that kills vampires working its way through Drexdenberg, Ronin knows he must do something to protect the people he spent a century serving.
Taking a job bartending job helps Adeline pay the bills, but when Ronin’s party gets out of hand, she’s reminded of the harsh realities of how hard life is—being one of the few shifters in vampire territory, and a single mom on top of it. Though the policy to integrate the races seemed like a good idea, Adeline quickly realizes that more than just her life might be at stake if she stays in Ronin’s circle.
While remaining in enemy territory seems like an impossible feat, leaving Ronin’s charming smile is a fate Adeline is unwilling to suffer.