Wow that something great to know. Ty for expanding my knowledge!
You're very welcome :)
Sangwoo's mom was sick way before she had him, she tried to abort him several times and it's implied she was like that since childhood.
The mother might have had postpartum but I don't think it was just that. I mean, she's stark-raving mad. Possibly, she was like that before giving birth as from what we know so far, her troubles run deep and long and got worse after she had a child.
There is also post partum psychosis.
Sangwoo said himself his mother was unwell sińce she was little.
Now we see why is so important to look for help if you're feeling down after giving birth. I suffered a mild case of postpartum depression and it makes you feel like your baby is a stranger who is there to annoy you and make people blame you for not being good enough. It is crucial to be well informed so you can spot the signs and treat it. If left untreated it can last forever in the worst cases.