Cynthialee.
I doubt anyone can not feel sympathy for you nor have seen themselves in your situation.
But look at it this way, you are asked to play a part, for one evening, for the benefit of your partner not to mention your home. I hope you don't think I'm being blunt here but if it keeps the old bird happy, in your position, I'd wear a donkey constume and bark.
I mean, treat it for the joke it is.
Most people would love to be themselves to the world. The reality is, few of us ever will. If I told everyone what I really think I'd probably have half the UK wanting to crucify me.
Just remember to stock up on some indigenstion remedies and might be a good idea to have a small packet of those suckables in your pocket. Apart from that, you've got a few hours of discomfort to keep some old biddy happy.
Good luck.