Yikes- that does suck. But I'm assuming this won't be the last of the meetings either. They have to be around each other for the wedding, the whole trip, etc. Better to get the meeting done and over with.
Not to mention, when kiddies get in the picture, I'm assuming they might be around each other for that too. Like birthday parties, etc.
The good thing- I'm sure they respect and love you enough to keep it civil. And I absolutely agree- keep the bubbly flowing. It always helps me in uncomfortable situations.