It is a sticky situation but honestly what I would have done is something like this:
Hey, John, thanks so much for all you are doing for Jumper and we sure wish we could stay and have fun at the party but we are moving in less than a week and this is my husband's only day off to help me pack. Im sure you know how hard that is! Again, thanks so much for all this...Jumper and friend are so lucky to have each other.
Bye now!
Then I would have gotten in my car and backed out while waving madly
