Reborn Heiress: Seducing the Regent

Xie Heng, infamous for his ruthlessness and cold-blooded actions, has the whole court shaking in their boots, praying daily to the gods to rid them of this little demon king. 
That was until one night, when someone spotted Xie, the young devil, locked out of his house, sweet-talking someone inside: "Come on, dear Jiu, open the door.  I'll kneel and admit my wrongs just for you."  
Moments later, the door swung open. The girl pinned him against the wall with a kiss, saying, "Big bro, play nice and I might just buy you a whole block."  
Xie simply smiled, letting her tease him without a hint of annoyance. 
The whole country was left in shock: Which deity had descended to tame him?  
In an unexpected twist of fate, Wen Jiu, the richest woman, finds herself reborn at fifteen and sold into the Xie family to bring luck and betrothed to Xie Heng's brother.
Her daily mission: keep his elder brother in line.  
Wen Jiu suggests, "How about we find a new hobby instead of chopping people up?"
Then, on her wedding night, Xie tied up Wen Jiu's groom, handing her a knife, "Finish him, and I'll make you mine!"