It was Jian's mother that killed Jitae's mother, Hajoon is just somehow connected to her, maybe poor kid, she promised better life if he does thing for her.
Look closely ch. 31. Hajoon beats Jitae's mom and ran away. It was their house why would Hajoon been there if he wasn't close to the family? And Jitae's mom was killed after hajoon out. I'm not sure that was Hajoon's mom or Jian's mom since she called her Miss. More or less like secretary. Jian is Jitae's half brother. So isn't that make his dad had relationship with Jian's mom first and then Jitaes? The one who stabbed looks like Hajoon. Suryeon is old now but i can see resemblance with women who stabbed Jitae's mom but not so sure who is it. Too much mystery
Jitae's mom mentioned that she used to work in orphanage, maybe he's one of the kids from there. But yeah Suryeon (Jian's mom) killed Jitae's mom, in chapter 24 Jian's mom is addressed as Suryeon when she's remembering interaction with Mieum's father in parking lot.
Let me refresh yall. Mieum's dad did this to Jitae because he needed money for Mieum's medical and future study. He's a bit weak remember? jian's mom promised sum money to mieum's dad in exchange he had to kidnap/kill jitae. hajoon told his mom about jitae & mieum so they hired mieum's dad fot this task. those 3 relate to this incident. Well hajoon was there when mieum injured. This psycho smiled when he thought it was jitae who died.
Jian's mom beat mieum's dad. She thought he was dead but someone hide him. I forgot who. Jitae didn't want mieum to remember not because he hates him but he didn't want mieum knew about his dad's crime (he was a good father to mieum so better keep it that way). He can't accept mieum's feeling cuz' he had to send him away to his dad (to keep his safety since jian's mom is looking for them too). Ughh.... Idk how mieum confront jitae. After all, mieum witness hajoon's mom killed jitae's mom. He knew too much and his memory finally come back.
Ps: is that jitae third leg on the last pic?ლ(´ڡ`ლ)