How?

I am completely freaked out today.
I am totally lost on Tuesday's meeting,
and I have no clue at all about what I gonna do next.
My boss can even see that I am stress,
yes I am,
and I am very nervous.
Not that I never went to any client meeting but this time,
those people that I will be meeting are the regional representatives of the brands,
and they are totally influential on all their brands.
Along with me I have my boss (the associate director), and a global CEO of mystery shopping.
Can you imagine that these people are really "business" people that I can't connect myself with them?
They all are successful businessman that share mutual professional experiences that I don't have (for now),
and I just can't understand their world.
Yes I know it is a great opportunity to learn,
but maybe I am just not confident enough?
I am not good in socialising (I actually don't like socialising),
but this time I gotta do it,
and most importantly,
it will be in English!
How can I not stutter under this kind of circumstance?

Trying to get myself prepared so that I won't look dumb during the meeting,
and that's why I am totally freaked out now.
Nervous + anxious + confuse + lost = don't know how.