I'm trying to remember where the story I'm thinking about is posted. It may be on Midnight Whispers, but I cannot remember the title or the author. It is a post 5.13 story where after Justin moves to NYC, Brian becomes depressed and very obsessed in controlling his diet. He loses weight and sleeps very little. The story begins when he crashes the Corvette while driving home from work one night because he's so tired and malnourished. Justin is called and is shocked at what Brian has become after getting back home, and he's angry at Brian for not telling him how bad things had gotten since he left.
Does this sound familiar to anyone? I'm hoping that I'm not combining elements of two different stories, because I also remember a plot line where Brian's cancer returns after Justin leaves, but I don't remember what else happened with that one besides Jennifer helping Justin take care of Brian while he recovers.
Update: It was "Temptation of Snakes" by
sapphire_3. Thank you
kmboatright for the quick answer!