what do you think holden means when he says,"i felt like i was sort of disappearing?

At this point Holden is crossing a road. We can tell that by now Holden, is clinically depressed. The day is overcast on a snowy day. This seems to exasperate Holden's melancholy. The coldness of the climate matches his deteriorating mental state. Holden has been expelled from prep school, he feels ostracized by his classmates and his teachers.Holden feels alone, his identity slowly vanishing.