You'll be alright. Your experience will be your own - your future roommate is freaking out right now too. Even the most social people I met (including my roomie that I am still friends with) expressed extreme self-doubt and apprehension when asked about how they felt before...maybe for different reasons, but no one goes in without their concerns.

Does your school have an orientation? We had a week long orientation (no classes, just touring opportunities, sporting event bus trip, cruise trip, interesting lectures, etc.) and taking one of those opportunities to get to hang out with your new roommate and experience the un-experienced together can be really helpful. That's how my room mate and I became friends, almost instantaneously... We went to a party 'cause we figured we should, being our first week at college and all...and after a while, we left our other roommate (who was having a great time) because we were bored to death and disliked there was nothing but crappy beer to choose from and bad music You never know who will end up a friend, even if you're complete opposites. Just try and make the best effort you can, rather than thinking "I am just going to hate this," or something, and remember there is no way of knowing. You might be surprised. It's college! No other way in but to jump, so might as well enjoy the view.