Me vs. Me

Here's the dilemma: I've been invited to a birthday party next weekend and I don't know if I should go. Under normal circumstances, when I've been invited to someone's birthday, I don't even hesitate to say yes. I have a thing about birthdays where I do whatever is in my power to make that person's day what ever they want it to be. Birthdays are special and I guess after having so many crappy ones myself, I try not to let that happen when it's someone's birthday I care about. So what's the problem? Well, it comes down to the fact that being around the birthday boy makes me sad. Every time I visit said boy, I get sadder and stay that way longer when I get home. What's worse is that the last time I visited him, he said he gets sad when he comes here, so he's stopped visiting me. Now the question is: do I continue to be the bringer of glad tidings and happy birthdays and come home depressed as hell or do I skip the shindig and suck up the guilt that I'll lay on myself for being selfish? As long as I'm stuck here between a rock and a hard place, I can avoid accepting my fate for a bit longer and at least enjoy wallowing in the mud...