So sorry that you have to go through that. I hate getting comments related to my body and food. It's so annoying and no one's business. I usually deflect any comments and forget about it. If they don't understand and/or empathize, then they can't be true friends.
Now, onto your game plan for being hostess. Start planning your menu from Heather's book. All of those recipes taste exceptionally well, and no one will notice that they are modified to fit your diet. You will be able to eat and probably not have to deal with comments from people.
Don't let them get you down. You are the one who has to deal with the aftereffects of eating something you're not supposed to. They may not understand, but they should accept.