Can't

I'm afraid i can't do it. i've been so insanly sad the last two days. for no aparent reason. i can't concentrate for more than a few seconds. i just end up closing my eyes and think of happy stuff. wishing myself back to either October 9'th 2009, march 1'st 2010 or June 2'nd 2010. it's the only stuff i can think of. it feels like the black never-ending tunnel is closing in around me again, and im constantly afraid that my depression will re blosom. i cannot deal with another depression. i am not sure i will survive it. well, physically i might, but it will chance me emotionally. kill my psykological self.