I feel so bad for Bum thou.....

(╯°Д °)╯╧╧

But technically, all of this was his fault in the first place. Im not victim blaming him but he brought it upon himself. He went so far as to breaking into someone elses house. Not saying he deserved it. But also he had plenty chances to report him but he didnt. All out of his selfish obsession with sangwoo

You know that the punishment for breaking into someone's house isn't abuse and rape?
Did you understand that Bum was severely mentally ill and he had no choice for most of his life? In season 1 he tried to escape several times but then he has been trapped in Jieun's murder, guilty and with nowhere to go.

Once again im not victim blaming. This happened to Bum because he was blinded by obsession. He broke into someones home not knowing what he was getting himself into. Bum was never mentally ill until he got kidnapped. He was traumatized yes but not mentally ill, He had plenty of chances to escape at the beginning but he wanted sangwoo to be with him. He also had the chance to report to the officer several times but didnt because of sangwoo. The only time he felt guilty of killing jieun was when they were confessing to the police and when they were burying her. Other than that he couldnt handle sangwoo leaving him and hating him. All this is just a bad case of stockholm syndrome (for bum) *i have bad recollection so i might have missed events where he felt guilty*

You probably missed that writing exactly at the start of the story: Bum has borderline personality disorder, plus he has always been depressed (maybe after the death of his parents) and the severe physical and sexual abuse he suffered by the hand of the uncle took its toll on his mental health.
Go re-read season 1 because he tried to escape at least three times, once he even attempted to poison sangwoo and his last attempt is in chapter 15, the same evening of Jieun's murder.