I've never applied at YC, but I've got a couple of failed startups under my belt. If you got a no, think about why, and consider it free advice from someone whose opinion you trust. If you disagree, then use it as fuel to work hard - as hard as you can; and show everyone else that when you were down on your luck you put your nose to the grindstone and made it happen anyways.
That being said, this isn't a win or lose sort of scenario; remember that it's a two way street. YC has certain types of companies or founders that they like to invest in; every investor does.
Take a few days for introspection, decide if you believe in what you're doing. If you do, then keep on slogging.
If you got in, then congrats... Start working on taking notes, because I hear you get an amazing amount of information from being a part of YC... even the face-to-face interview portions.