The Archvillain's Daughter-in-Law

I've reincarnated as the young daughter-in-law of a villain who was taken in for his deceptive plans. The problem is that I'm terminally ill, so I'm going to die when I become an adult. "Luckily, I know how to cure it, but..." If I don't die at the right time, my father-in-law—no, the villain, Duke Ecarde—might kill me just to achieve his goals! But what kind of kid could actually adjust to this kind of household? "I want to live happily with Father and Evan for a long time... cough! Cough!" Me. I'm "that kid." --- The final villain is being deceived by his young time-limited daughter in law who was possessed. If I die at the right time, I will marry his son. The problem is, I already know the cure! And I don't want to die, but if I don't get killed now, then I won't die quietly. "D...