The originals are HERE.
I say, I will forgive your stupidity because you are a child. Your friendship with this girl is going to last a few more months, tops, and it's not very friendlike to put you in the position for lying to cover her misbehavior. Please tattle away and get the guy locked up.
I came up with the same idea, but even lest loose with the truth: say you were working at a bar. Do you really need us to come up with this white lie?
I say: why is it always the women who have to deal with the MIL? Where are the husbands? If the straights want to keep marriage to themselves, they need to start doing a better job of it!
I say this is a great pity. This family is now part of your own Xmas tradition, and I would hope you might find a new way of celebrating. If you can't fit everyone around the table, how about a buffet or something? Or two services, one for the kids and one for the adults?