The Regressed Villainess's Vow of Chastity

Lydia Evanshi had everything a noblewoman could wish for: an illustrious marquis lineage, wealth that could sustain generations, and a beauty fit for a portrait. The only thing she lacked was good taste in men. She threw her whole heart, soul, liver, and gall into supporting a prince of low birth, even helping him achieve his dream of becoming emperor. And he repaid her by having an affair with her distant relative, Giselle.

So Lydia made a choice, she and Giselle would drink poison together and show them what true obsession looked like. But the plan failed, and Lydia was hauled off to a brutal, desolate labor camp. Not long after, a plague swept through the freezing compound. With her thin, pale hands trembling, Lydia quietly waited for death.

"Why had I lived so foolishly for a man? If I could go back, I'd slap myself hard enough to crack my own jaw."

...And then, her chance arrived. She woke up on the very afternoon she had slipped poison into Giselle's teacup, tea time itself! Smack! Lydia immediately slaps her own cheeks awake and begins her new life. A new life where she will avenge herself on Richard, who abandoned her, on Giselle, who betrayed her, and on Devon, who bartered with her life. For that, she needs Arsen Edith, the empire's coveted sword. Lydia seeks him out, declares without hesitation that she has returned from the future, and asks for his aid. Arsen, doubtful yet intrigued, chooses to watch her closely and begins living alongside her. But as days pass, Arsen's gaze toward Lydia begins to shift into something entirely different.

(Source: Kakao Entertainment, translated)