when my birthday rolls around I get more and more depressed.

I am turning 27 this month. Every year when my birthday rolls around I get more and more depressed. I just don't see the point of continuing. Here's why: I have never had a birthday party, I have never spent my birthday even hanging around with my "friends"...nothing. I rarely even get Facebook messages anymore. I try to invite my friends to do something: hang around at Six Flags, go shoot pool, or even just go for some drinks, but every year my invites get ignored and I end up sitting by myself. I've also tried to reach out at CraigsList and other dating places (I've never been in a relationship, which just makes my depression more painful) but all I get is spam. I feel totally alone, and I can't take that feeling anymore. I always end up thinking that if nobody else cares, then what's the point of going through another one?