It looks like it's him to me too but that sure doesn't make sense, how could someone that seems so responsible could become the ahole we see in the present (all I can think about is either he's faking it for money or something, or somehow the fact that Dojun is such a great person put them all to shame and they became so jealous they transformed into giant piles of turd)
Think of it this way: Money corrupts people. He may have been initially distraught by seeing the starving kid that he came in like that in the past, but once Dojuns brother started sending funds, he realized that he could make bank by keeping Dojun under him.
The guy who stormed into the hospital room?? Bc he was sounding reasonable there...what happened that he became such a pos - was that supposed to be a nice guy act?