I picked this quote because I believe that Finny felt like this when he returned to Devon. When he found out Gene was going to leave him to go to war, Finny felt hurt. He felt he wasn't as important to Gene as he thought he was.
'I'm drowning and you're standing three feet away screaming "learn how to swim! - this is how being depressive must feel like. Horrible feeling for the screaming person as well - I know what I'm talking about.