Sangwoo said "You are just like her", like his mother, he probably did the same with him father in front of his mother and she probably said the same thing Bum said "I didnt want him dead, just wanted never see him again" I dont know what happened with his mother, I dont know what will happen with Bum (⊙…⊙ )
I think all of this is punishment. SG is all flowers and all for Bum to feel like he cares, making him believe that he is jealousy and have some sort of feeling for Bum. "I win" was cuz he knew that Bum fell right into his trap, got the bait very easy. And when Bum thinks that everything is perfect, that is when SG will make his move. His punishment. He will make Bum pay for all that police story, or any other thing that I dont remember.
Okay but why nobody is talking about the scene where his mom appears naked at the shower, like he was intruding into the bathroom? (⊙…⊙ )