Trust me, you'll be fine. Stop worrying so much, if I could hug you right now I would.
I was and kind of am the same like you. I worried about how things would turn out, always expecting the worst and when the moments went by in the end I made them out to be much worse then what they really were.
All I can really give you as advice is try to go to that class and see what happens. And please please please stop worrying so much or I'll get worried too.