Responses
I still think that Sangwoo will die. It was hinted at too much to not happen
As for why Bum did that, remember that nobody taught him anything, his parents were died since he was like 4 and the only thing he receiver was abuse.
He thought that what he did was showing that you love someone, he didn't intend to harm Sangwoo.

I doubt they would go to jail , they not mentally stable enough for them to recivie sentence , it either go to mental hospital for life or do double sucide , but while reading all this , their was one question in my mind whole time , why did bum enter that house ? , no matter how you obessed with someone you don't just go and enter people houses , since the very begining something was not mentally right with bum , sangwoo intense just push bum mental off cliff , but before all this happen bum was mentally unstable .
Something else , I only read chapter once and don't dare reread them , it mixed of scared and not wanna go though it again feeling .