The Villainous Bosses Mentoring System

I don't remember her ending being shown, only her mother pleaded saying, stepsister was innocent of true wrongdoings and was only impulsive, so she was sent away and ordered never to return in front of the villainess...though I remember her parents being sent to prison...
P.S. Although the villains' love story was shown, though I felt it was forced... but only the Villainess love story wasn't shown... 

Oh sorry!!! I misread after I saw the word "bro" orz. Uhh sadly I don't really recall but I know he wasn't close to MC's age at all. I think it was in the range of 8-13 but I honestly don't remember since he really wasn't that important in the story... He was just... there playing video games. Grandpa He literally had my blood pressure rising when he tried to control MC's life like how he did with Mother He. Luckily, MC didn't listen to him and he backed out in the end. What kind of person would tell someone who was cheated on to get back with their cheater... But yeah, I seriously felt bad for both mother He and grandma He at the time, especially when seeing someone as old as her (grandma He) still crying when thinking about the past when she was cheated on too... But in a way I was a bit disappointed in her for not saying anything when she knew how it felt when being cheated on yet still watched grandpa He try to force Mother He to get back with the dad Su... 

Spoiler please 

What happen to the step sister of the rich missy villian? 

No. Unfortunately, the way Su Tian treats Liu Kaiyan like a brother or a close friend. Su Tian just doesnt see Liu Kaiyan as a potential partner since she’s concentrating on her task. 

So who’s the ML?