The execution could've been better..... but it feels like Fargo-nim forced all ideas into a short chapter.
Hyesung prefer to forgive his son thinking that Byul knew everything but I actually think he actually didn't know the entire story yet from his father. He was probably told that the grandma abandoned his mom, but not knowing how his mom tried his best to survive only to get pregnant all of sudden one day.
Not just that, when his grandma decided to meet his mom gain, she blamed him for not looking for her instead. Also getting told that my face looks the same as someone I hate is a big insult, so I don't get why they acted like saying that sounds great to hear.
I still blame the entire problem as Dojin'a fault though. He knows EVERYTHING but he let Byul saying that.
What makes me kinda believing Byul doesn't know the entire story is because he hoped that Hyesung will want to meet his mother again one day. I mean, if he loves his mom so much, he should be get mad knowing what actually happened in the past.