To think a simple "x can't attend the party, sorry" would have done

[dilemma456]

Message withdrawn

I don't think you need to reply. I agree with an earlier poster-laugh and move on!
Unfortunately you have to feel very sorry for the poor DC.

I broke my leg on a 5-legged pub crawl once. (though to be fair I wasn't 3 yrs old)

Stick the reply on your kitchen wall so all can enjoy.....