Noroi de Neko ni Sareta Akujo, Outaishi ni Hirowareru.

Lililucia, the daughter of a marquis, scarred her younger sister's face when she was young and was made into the most evil woman in the kingdom. When her sister got married, Lililucia decided to stop listening to her own selfishness and reform, but her sister cursed her and turned her into a cat! Lililucia, now in feline form, is picked up by Crown Prince Gerald, who loves cats excessively, and ends up being sweetly doted on! (Source: Futabasha, translated)