Is ch64 a flashback?? It shows us different timelines nd im confused

Yes and it's likely the "car accident" that caused ML to lose his memories

from what i understand, this is after yoonsung got out of the hospital after the car crash. hes thinking about the good times they spent together before killing himself. my guess is that this is the reason he lost all his memories

Omg. It better be a flash back! If this is the present, I don’t know how I’m gonna go to work with my tear stained, swollen eyes.