Have to preform infront of a lot of people!!?!?!?

So I am going to be performing onstage with a diablo. (a diablo is a Chinese yoyo) and I am really scared that I'm going to mess up. I can do all the tricks fine, but when my brother or parents watch me, I get nervous and drop the diablo. How can I not drop it when I preform in 3 days?