Miss Mermaid

Eun Ah Ri Young is a successful drama writer with a scarred past. When her father had an affair with another lady and left the family, her brother died, and her mother became blind. Hating her father her whole childhood, she grows up planning revenge on her father's new family.
Her father's new wife, Shim Soo Jung, is a popular actress. Ah Ri Young writes a drama about the affair and her blind mother and casts Shim Soo Jung in the role of her blind mother in order so that Soo Jung will feel guilt. Ah Ri Young also plans to steal her stepsister's fiancee.
A guy she only chose for revenge becomes a guy she truly loves, and that love confuses her feelings for revenge. Jo Soo Ah, her mother's friend, helps in the revenge because she wants Ah Ri Young to become her son's wife. As one person's plan for revenge starts, many people will become hurt, and the true meaning of forgiveness and understanding is learned.
(Source: DramaWiki)