This might sound biased coming from me but let's just say he used to have a very big ego, foul mouth, loves money, and stole someone else works for his own profit.
Also trying to manipulate Doona saying her novel is shit (even tho it's good) so she didn't succeed and rely on Minho.
There's more to it tho I read it a long time ago but my memory is a bit blur.
The point is yeah he is an asshole that deserve punishment, but he didn't deserve THIS much of punishment.
Even for Minho this is too much.
The Author LOVES to punish men so much, This Manhwa and Reverse thinking.
It's basically fetish at this point.

Also even if this is a side story, don't bother trying to read the main story, it's not worth it.
Long story short Minho is an Asshole and he is Doona ex but Doona is like a girl who Loves BDSM (She use Violence too in some cases) since the main story is like reverse harem so ofc she (the MC) sleep with a lot of people but Minho is definitely one of her favourite boytoy.
Wookyung also like and fuck Doona too iirc? But there's some chapter where he think Minho is kinda cute/sexy too.
Then both of them Broke up, Doona become a successful Writer, end up with someone else, Minho make a huge mistake, then he went crying in the corner while no one watching.
Wookyung then accidentally take a peek, since he Never see Minho cry so miserably like that before it makes him feels something and that is where the mess of this side story begin.
Sorry if there's something missing, I'm trying to forget that mess of a main story.
The only reason I read the main story is because I want to see how much of an asshole Minho is but now I regret it. ┑( ̄Д  ̄)┍