I know exactly what you mean. I do the very same thing. I want to go out and do things, but then I always change my mind. I just cant stand going out into the crowds, public I guess. I dont know, but I get really upset with myself. Its a viscious (sp?) cycle. I am always worried about what my friends will think. They probably think, 'why cant she just come'. 'Whats the big deal'. 'She could force herself to come if she really wanted to.'
But, it isnt as easy as that. And it doesnt make you a bad friend. Luckily, a few of my friends know and understand what I am going through so, they encourage me to go, but they never force me to. They always tell me to try, but if I just cant, they understand. I like that! Hopefully, you have good friends who understand what you are going through.
But, I totally understand what you are saying...