Ice Queen by Candace Wondrak

A land covered in ice, a desolate wasteland of snow…a kingdom with no queen.

Frost used to be a princess, but she is royal no longer. Her homeland of Wysteria lies in an eternal winter, all because of her curse—something she was born with, something she could never truly control: the power of winter itself.
Her life becomes a tale of misery and loneliness…until three handsome mercenaries stumble upon her and claim her long-lost sister is alive and now the queen of a neighboring kingdom. And what’s more, her sister needs her help.
To go into the heart of Wysteria, Frost will have to brave the mistakes of her past and learn to live with what she’s done. Fortunately for her, her three mercenary escorts are more than willing to protect her body and her heart.
Learning to love just might save the kingdom from destruction.