I do agree that you may have opened Pandora's box here...I imagine to tell her to close it again will be difficult, and even if successful, will ultimately cause resentment.
I do think that perhaps your wife and the other guy could have tried harder in that situation.
I would like to think that she would be trying extra hard to get you involved in a conversation with him, where you think 'actually, he seems like a really good guy'...instead of this awkward situation you describe where you turn up and they are all over each other, and you feel like a spare part.
In that situation, it seems to me like you would have to feel like you were breaking up their party, just so you could talk to them. You probably know that the other guy doesn't likely want you round that much either. I don't blame you for getting out of there.
Perhaps you could put that as a suggestion to her for next time? (if there is a next time)