The nerve of this group to be using poor google translations whilst asking for donations. PLEASE let someone else who's less problematic take over. There's no point to anyone reading this story if we can't understand it. What purpose do the proofreaders even serve?? Of course I'm incredibly grateful for the translations, but when you're half-assing the job you might as well stop and let us wait for official English translations. (And yes I also support the author by purchasing their content).
Obviously this is just a guess because it is a bit confusing, but my understanding is that because Gyeong Joon is Cain's door, the Doctor was using the power of his soul to help heal Cain. I think Joon's soul was being destroyed through this process which was why he was disappearing, but Cain pulled him through and forced himself into consciousness quicker so that Joon's soul wouldn't be completely destroyed by the process of fully removing the bullet - the dr mentioned only removing half of it.
I really have no sympathy for Chowon. Mental illness or not, he's selfish, immature and wants everything his way. He doesn't deserve forgiveness for his actions. That said, I want him to start taking accountability and heal from his potential traumas. He needs serious psychiatric help. Once he's in a better place then it would be good to see him move on and find comfort in Kyungsoo. As he is now he can't make either of them happy.