If one of your friends told you she had social anxiety/avoidance disorder, how would you react?

I have that disorder too, but when I told one of my friends about it and explained it a little, he was really understanding. If you just tell them you have it and explain what it is a little, like how it affects you, I'm sure they'll be really understanding and they'll support you. Some will support you more than others, probably, but I don't think anyone will tell you you're crazy because you have that. It'll probably help them understand you a little more. They'll be able to help you through the times when it's really hard on you. Good luck with it.