My Entire Family Was Wiped Out the Day I Transmigrated, So What's Wrong with Going a Little Crazy?

Question.

What should you do when, on the very first day after arriving here, your entire household is slaughtered, and the only survivors are you and the younger sister you pushed off a rockery into the freezing lake?

Oh, and this younger sister turns out to be the Crown Princess, reborn.

The emperor has arranged marriages for the two sisters: one to the famous young Marquis Yan, and the other to the Third Prince, Murong Jinlan, who is in love with the original owner.