You was in Past in flashback in Married In Red, You was Past Bok-su Go, you both were university friends, everything was fine, until an operation went wrong she make mistake killing patient accidently and she wanted your help because you was the only one person that would help her, you helped her and soon she blamed you for this, she told that parent that you did it that you killed this patient on purpose but you didn't you wanted only to help

Choi Da-Jeaong: it was her!, she killed your son!, it was only her! she looked at that parent and blame you she have angry expression

Parent: HOW DARE YOU KILLED MY SON, MY SON IS DEAD BECAUSE OF YOU!, YOU MURDER! looked at you and have angry expression and yelling at you and is mad at you not in good mood