Blind girl solving why her stepsister committed suicide – Please help with the title

Blind girl, who was adopted, figures out that her stepsister was molested by her own father when they were children. The girl committed suicide and left a suicide note giving her clues for evidence and the reason why she killed herself. The blind girl also catches father molesting his other daughter as well in the swimming pool one day. She tells their mother about the letter, which makes her overdose her husband with his insulin medicine because he has diabetes.

I might be confusing some parts or roles, but mainly this is the story.

Thank you for anyone reading this! I hope someone can help me find the Title!

Have a lovely day everyone!