Regarding the Perfect Revenge

Roxanna spent years grieving her first love who supposedly died at the hands of her father, a greedy and cruel nobleman. However, when her household is annihilated, she discovers that the man who led the downfall of her family is her first love, Curtis. No longer the gentle boy Roxanna once cherished, he has transformed into a cold, formidable warrior driven by a calculated thirst for retribution. Since then, Roxanna is content to live humbly and quietly in a nunnery. However, as circumstances bring her and Curtis to reunite, the desire for vengeance rears its ugly head once again.

Original Webtoon

Official Translations:
English, Japanese