I had an almost identical situation. The first real job interview I ever had was a panel interview that I was flown to a foreign (non-English speaking) country for. I had a lot of the same fears as you, not to mention the fact that I felt extremely under-qualified for the position. I pretty much broke down right before the interview with thoughts of "I'll never get this job in a million years! Why am I even putting myself through this? There's no point! I should never have agreed to do this. I should just forget about all this and go home."
I ended up somehow pulling myself together and even got the job. A few years later, after serving on the other side of a few interview panels, I've realized that there isn't so much to be worried about. I know it's difficult, but it helps to realize that the people interviewing you are just people. They aren't better than you. Some of them might even be as nervous to be on the interview panel as you are to be the interviewee (like I usually am). They aren't judging *you* as a person, they're trying to decide if you'd fit with the open position they're trying to fill. It's just a job, and there are lots of those out there for you. They've obviously seen something they like if they've invited you to come interview in person.
I wish I could be normal, too. There are lots of situations that cause me so much anxiety that normal people seem to get through with ease, even look forward to. I'm not sure I'll ever be truly normal, though. The best I can do is try to work through it.
I hope your interview goes well!