Just read all of it today

IKR? I am so fucking tired of readers painting Woojung as some kind of victim.
Victim of whom? This must be the first story where a homophobe is on canon treating his brother as a dog shit that he scraps out of his shoes and fans feel sorry for the bully.
The things he says to Sarang: "You are disgusting". "Pretend you don't know me in school, being your brother is shameful enough". "Gay Freak", "Filthy". And he even attacks him physically ( Junwoo took the hit for Sarang but that punch was for his brother). And worst of this all is that he whines that he is the victim of his brother --- that his brother being gay split the family when he and his father were the ones who rejected the brother. Whatever he went through his brother got it twice over. He grew up with one parent? Guess what? So did your brother. And he did it having to feel like it was his fault. What exactly did he want? That Sarang 'stopped' being gay for him as if it was a choice? Being gay wasn't a choice but being homophobe or at least be compassionate certainly is.
And it's not only the fact that he is homophobe but also how selfish and immature this dude is ... from the start, all he does is whine in self pity about his brother being gay and 'ruining' the family and trying to make the girl happy because she is the one that matters to him. And people knows very well how to blame the father for being a homophobe but they excuse Woojung for the same thing. If you are going to tell that Woojung is a homophobe because his father taught him that --- okay, I may agree but why his father then doesn't get the same absolution? He certainly learned from his father and being from an older generation makes his homophobia a lot more expected and 'excusable' than his son who lives in an era where he could very well make his own path if only he wasn't so hung up in how everybody else is mean to him and how much of a victim he is from everybody. His demands that Junwoo rejects Sarang for his sake and then go pay attention to the girl is beyond ridiculous. This guy needs a diaper because he never grew up.
Junwoo had issues with family and he isn't going around whining and blaming anyone. Sarang had the same issues that Woojung plus much worse because Woojung is the one who spits on him and he didn't grew up whining that his brother rejected him. Woojung's mother -- that probably did what she had to do to save Sarang's from some kind of horrible destiny like suicide or danger -- takes the blame. Sarang takes the blame. Even the homophobe father recognize his flaws and mistakes. Who is the only one that can't see anybody's else side but his own? Woojung and that girl are so much alike --- their main traits are being selfish and self centered. That it's a pity that she doesn't like him.

I'm glad you don't like Woojung as much as I do because I was surprised to see people rooting for him. He honestly has no redeemable qualities. And it's so funny that he blames Sarang for splitting the family up. Woojung could have made an impact in that whole situation by standing with the mom and Sarang. If he did that then the father would have to realize he is literally losing all of his family over his bigotry and maybe he should be more understanding. But because Woojung went with his father, the father was able to feel justified in some way because Woojung agrees with him. He has such a victim complex and has essentially spun it around to where the mom and Sarang feel guilty for doing nothing wrong. I overall just think he's a terrible character. He and his friend Seohee (is that her name?) would make the perfect couple. She threw away her friendship because of a crush. Girly the guy is GAY. She is forcing herself on him like what kind of relationship is that? And the two of them are acting like people can just turn their gayness on and off. Sure go ahead and turn that hetero switch off, oh wait - it doesn't work like that （￣へ￣）
Let me tell you some of these characters really stress me out haha!

Well, in a way, the mother has a bit to apologize for. I mean, she argued with her husband for Sarang but that didn't mean she had to cut ties also with her other son.
She could've lived with and supported Sarangi while meeting Woojin sometimes. She left him alone with his homophobic father, so it didn't help Woojung in stopping being homophobic too.

It's just a bit sad because if the mother had tried to keep her contacts with both her son's, probably things wouldn't have been so bad

Who said Woojung wanted contact with his mother?
If he acted the way he did with Junwoo, now that he is an adult, and said that either he rejects his brother or he will not be his friend anymore, how much more childish do you think Woojung was before?
I can't believe people are actually putting the blame on the mother's back. Woojung was bullying his brother at home. The mother, just like Sarang is assuming guilt that she may not even had. Everybody is assuming blame, either is deserved or not, except for Woojung who was an aggressor both in the past and now that he is a grown up.
Also, it is clear that the mother loved both sons. I find really hard to believe that Woojung wasn't just as aggressive towards her in the past when she 'chose' to leave and support Sarang.
It's time Woojung own his own shit, his responsibility in the family split. He could very well have stayed by his brother and mother side. He rejected and bullied his brother and he never grew up from this. Still now, a grown up he sees himself as the only victim of the ordeal.
If we don't hold Woojung responsible for his adult homophobia because it is always somebody's else fault, then we can't held any homophobe guilt of ignorance because it's not like they were born like that. Once you are an adult, your sins and mistakes, learned or not, are your own.