At the end and in chapter 47 which I think is the coniburation of that scene Linzo
Correct. In the end, Woojin is remembering that hospital scene (which seems to have taken place a few years ago) and what he told his half-brother back then. That it doesn't matter if Min Woojin no longer exists because in the end everything he did was for the boy currently in his arms, Taemin.
Like when does that hospital scene happen and wtf does it even mean it doesn't make me any less confused