Honesty is the best policy!

When I was a child if I ever got into a room where there were more than four people I would get nightmares and the hot sweats. There was a mountain that was going to get me and hurt me. This went on for years and I finally out grew it. I think the reason for this had to do with a friend of my mothers who would let me sleep in her lap in the middle of the party, or wherever the couch was. I volunteered for a part as an extra in a movie and I came to have the same attack, I told the person who I was to answer to that I had a condition where I just start to freak out and get sick. I made my excuses and left, everything was OK. Some times it is hard because you think you are letting someone down, or not participating as you should for a friend or acquaintance.
I am having some trouble explaining further as there is more to the story than I am letting on. I think the best thing that can be done is to be honest with yourself and do what makes you feel the best.

I explain I am not anti social, I am just NOT social.

I usually slip out a side door and vanish, about halfway through it. (Anyone else do that?).

On the rare occasion that I get invited to a party, I make every effort to go. It's nerve-wracking and anxiety-producing but I go. Sometimes it's fun. I think things can be anxiety-producing and fun at the same time.

i'm that way too. or you cam make a quick appearance and then leave -- with a prefabricated excuse

Are there any other dogs coming so it doesn't look like I peeded in the corner?. (even if I did)

I love small groups, but hate large, noisy gatherings. My work has often entailed attending large functions, but fortunately it also meant I could usually invoke some reason for not staying too long.
In small gatherings it was the hosts who had to think, desperately, for a reason to throw me out!!

Because I don’t want people to make the assumption later on that they shouldn’t invite me, I just handle each invitation individually. It may be something I really want to do or someone I want to see for other reasons. It makes it easy right now because invitations are few and far between.

I try to drink my way through it.

Well done . I find that unless I really work at trying to make friends , everyone pretty much leaves me alone . And even then , when I work at making friends , it seldom works . Having aquaintances , is not the same as having friends .