Do your friends know you suffer from anxiety?
I had to go on a hen (bachelorette for Americans) weekend abroad last year and was equally anxious, and thinking of cancelling. But I was the maid of honour, so that would've been hard!
I told the girls honestly I was dealing with a lot of anxiety, and was surprised how many of them replied that they had dealt with it in the past, or were at present taking medication for it. They told me if anything became too much, to just let them know. And that really helped calm me.
I know it's typically different among guys. But any way you can let them know what you're dealing with?