You are Mafia King's Substitute bride. He was forcefully Getting married to your Twin sister but you helped her to run away. When your family got to know that you were the only option to save their life and pay their debts. So they used you saying that you're your twin sister. You had to hide your identity and Live with a monster..but slowly you'll find out the real him, he's a gentleman.

"Choose any room you want Lia" he mentioned your sister's name which was weird for you