The Justice of Villainous Woman manga summary:

The day I lost my boyfriend to my best friend, I fell into the Han River by mistake.
And when I woke up, I became a famous duke's daughter named Chartiana Altizer Cailon - who's known as the villain!?
"I've already chosen my empress, and you're just pawn."
"I will be the empress of the Empire."

My fate was also determined the moment I was appointed as the next empress candidate by Regina.
Regina has two candidates, Irene, who is the lover of the Crown Prince and me, Chartiana.
To protect my beloved family from the court's evil schemes, I cannot help but become the evil villain and win the position of Empress.

To be happy with the people I love, I became the antagonist.