Comment by MissMango on Lucky Paradise - Chapter 78

I think the writer was trying to portray chunwoos  feelings through this interaction . The anger the sadness desperation and the love he felt. As well as that I feel like chunwoo was trying to make him feel what he felt when they were together, by acting like him and making him feel worthless. 
In my opinion it was a way for chunwoo to really move on from the toxic relationship and heal.
(only my personal opinion, don't have to agree with me) ^o^