Can someone explain to me what is happening I’m genuinely so confused???? What is going ...

What exactly r u confused about? We are still in the past flashbacks. We covered that Yuwon apparently was ran over by Hanseob (Dohun's brother) seven years ago and it damaged his brain. Ms Choi, the new coworker, was the one to get him help as it seems and that was why she said that Yuwon looked familiar. Hearing Ms Choi state that Yuwon looked familiar, Dohun probably guessed that it had something to do with the crash. After that Dohun's just losing his shit because Yuwon is still unhappy. (Yuwon interprets Dohun's help as being forced into isolation, thats why he's mentally unwell). We are getting close to the present timeline