It sounds like they're both telling half truths. The mom basically confirmed that she did abandon Hyesung, so the dad wasn't lying about that part. Saying that Hyesung is the reason she left was a lie though. We already know that she left the dad because he was an abusive jerk.
Oh I just had the feeling that hyesung was an unreliable narrator when it came to his backstory so I really didn't know what was true.
Oh I didn't even consider that Hyesung could be an unreliable narrator. I just assumed what happened to the mom was pretty much the truth, since the dad was abusive to Hyesung too.
I am curious about which of his parents are telling the truth. I mean fuck then both for only coming to find him after finding out who he's married to but still.