Basically he staged shinwoo's death with help of his older brother, which gives him some time to find out something against his dad to blackmail him to not force marriage onto him. He returned to Office to find out a dirty secret about his father past and found that letter. I think the letter says something about the incident with an interpreter (might be Shinwoo's father) who died i'm prison for something that we don't know yet and how all the testimonies were dismissed and the case closed. I hope You can understand (sry English is not my first language)
And also he is hesitating to be with shinwoo because his father might found out about it, since the staged that and all that (+_+)
(๑•ㅂ•)و✧ thank you so much! Reading so many different manhwan, yaoi, ect. I get the stories mixed up or forgot especially when there's long period of times in-between chapters ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄
So im lazy to re read the chapters, but what was on the letter that hyowon found and why is he hesitant to be with shinwoo? （￣へ￣）I missed something