Betrayed? I Chose the Dark Lord

To protect his new lover, my Paladin fiancé gifted me to the Dark Lord, mocking me as a brainless beauty. He forgot one thing: I am the true source of his magic! Betrayed, I tore off my holy robe and leaped into the villain's arms. "I will be your Queen!" With my full power unleashed and the Shadow Lord by my side, I’ll drain my hypocritical ex's power and watch his empire burn. The supreme witch has returned!