The panic reaction of an introvert in a crowd of not-strangers

I cannot be a chameleon in a crowd of plaid

How do I tell an old friend
A classmate from back in the day
Who thoughtfully and well-meaningly invites me
To a class reunion,
That I am in terror of the crowd
The known crowd
The friendly crowd
The crowd with faces and people I know
I knew
I might know
I might remember.

I can deal with normal crowds
Faceless crowds
Crowds with obstacles not real people 
Crowds with interactions limited to “Excuse me”
And meaningless smiles. 
I flow through those crowds 
Water through pebbles
Untouched and unaltered 
Emerging at the other end.

Those crowds mean nothing.

Gatherings at church. 
Large parties of acquaintances and family. 
Class reunions. 
Who are you? Do I know you? Have I met you?
How do I treat you? 
How do I talk to you?
How do I know what you want from me?
How do I get out of this?
How do I get out of here?
How do I get out of here?

How do I get out of here?!

Please, God, let me out of here.

I can do persons. One, two, three at a time.

I adapt. I reflect. I blend.

My accent changes. 
My speech patterns meld with the conversation. 
My political and social views are nothing but smooth edges.

I smile and nod. Smile & nod.

I am a social chameleon, I am I am.

I cannot be a chameleon in a crowd of plaid.