Man, that's rough. I had about a 5 year period where I was the same way. It was like clockwork, every year on my bday something bad would happen. Not like someone i was close with died, though, thats awful, but for me at the time, it always sucked.
18 - engine in vehicle blew and was stranded on a remote hwy without a phone
19 - found out g/f was cheating when she wrote an email to the dude but accidentally sent it to me
20 - got a concussion
21 - spent morning in hospital with kidney stones, then after getting released that afternoon, the friends that came for a bday get together I had planned all bailed on me for another party b/c I wasn't physically able to drink.
22 - g/f and I went to outback for dinner, she dumped me over the cheese fries and bailed; found out 3 days later she was screwing around with her roommates boyfriend.
By 23 I avoided acknowledging the day like the plague and my friends knew not to say anything to me until after it was over. Had a couple of uneventful years in mid 20s that I attributed to avoidance and lack of acknowledgement. Then got married, had a good bday that year actually, deployed a year later, and right around the 6 month mark while overseas my friend handed me photos of my now ex-wife sitting on a dude's lap in a bar. It was the day after my bday, but they were taken by someone and posted the day prior, when my buddy found them online. I immediately went back to avoiding my birthday
It wasn't until my early 30s before the curse seemed to wear off, but I still dont care for birthdays. But to end on a high note, my current wife is infinitely better than the old one. And about that girl that dumped me over the cheese fries and started screwing her roomies b/f... well, her roomie (who was a good bit sexier than she was) came to me for a shoulder to cry on because we both found out at the same time. Needless to say I got over the g/f in a manner of hours