One of my favorite quotes is in my signature: "if you risk nothing, then you risk everything"

I think it very much applies here! If you don't go out to your party, you "risk" not being able to enjoy yourself on your birthday like you want to. If you go ahead with your party, there is a risk you will be depressed and you won't be able to enjoy yourself on your birthday like you want to.

Risk wise, there is no difference whether you want to hold the party or not. So, I say go for it! You have nothing to lose.

Besides, if you end up depressed, I think you'll feel a lot better knowing that you tried. If you don't try at all, you may be wondering what you could have missed, and then there may be guilt and regret (not to scare you).

Just my 2 cents!