For those of you who don't know what the grandmother did:
1- She abandoned Hye-sung when he was 5-6 years old.
2- Her husband, Hye-sung's father, was abusive but that wasn't the only reason she left. She found another alpha (female). She left Hye-sung for her new alpha.
3- She didn't say anything about Hye-sung to the new alpha because she wanted to start a new family. Hye-sung was nothing but hindrance for her so she kept him secret. (People tend to forget this part.)
4- According to her (I don't know if we can trust her words) she wanted to talk to Hye-sung after she left but the father convinced her that Hye-sung didn't want to see her. (a 6 year old boy ffs.) She said "ok" since it was convenience for her and never ever bothered again.
5- After so many years she saw Hye-sung with a crazy rich alpha and tried to meet him. She had the audacity to blame him for "not looking for her". Yeah, she said this.
Hye-sung decided to live his new life without the shackles of his past but i'm afraid Fargo wants us to believe she's not that bad.