Sister-in-law of the Heroine in a Childcare Novel

I was reincarnated as a minor villainess in a fluffy, family-healing novel. Specifically, as a pathetic imperial princess destined to become obsessed with the adorable female lead’s eldest brother, only to end up poisoning the female lead and meeting a miserable demise.‘Fine! I’m dumping all of you first!’ With that vow, I was all set to pack up and flee. But after accidentally saving the female lead, things went...