Whos the guy on the bed... Is he the guy committed suicide that day???

No he's the brother who was sick and died you know the reason why min woo Jin had to leave

It's Min Woojin's sickly half brother, that he replaced.
Si Won is the boy who committed suicide.
Min Woojin is the blonde guy before he gets taken in by his father to replace and live as his dying son, Si Woon.

Thank you so much for enlightenment guys