Bitter Burn by Sierra Simone

I think it’s important that you know this about me, that you understand this: I’m not sorry.
I’d do it again.

After my husband died eight years ago, I made vengeance my only purpose, my religion, my destiny. But to get to my enemy, I had to make myself like him. He had a kingdom of secrets? Then I would make an empire. He had blood on his hands? Then I would bathe in it.
But Tristan and Isolde changed everything. I hadn’t counted on wanting them, needing them; I hadn’t counted on how it felt to watch the two of them fall in love. I’d thought I had everything under control—I’d thought I was safe from my own long-dead heart. I’d never imagined that the wronged husband, the jealous king from my childhood fairy tales, would be played by none other than me.
It no longer matters what I used to believe. My enemy is ready to finish the game, and for the first time in eight years, I have pieces on the board I can’t afford to lose. I’ll burn the entire world to keep Tristan and Isolde safe, I’ll scorch the earth—but as any good assassin will tell you, fire will only get a man so far, because there’s always something left in the ashes. And for the three of us, it’s the cold, bitter bones of the truth: their story begins and ends with me.

And every story needs a villain…