If you ask him out first, you will more than likely lose a friend. If you share your feelings with your friend that you have for this guy, she will more than likely be upset with you for "falling for a guy she likes" and it will hurt the friendship to some degree, even causing it to become non-existant. If you do nothing, move on from this, and look at another guy that none of your friends like, you will end up with your friends and a guy and more than likely happy.

The choice is yours, young one.