Deb,
I think you're smart to avoid eating out. I do eat out, and have almost since the beginning, but it is definitely a potential risk - probably the "weakest link" in my healing chain.
You are entitled to your privacy. In my opinion, no one is entitled to judge what you eat (it's not as though GF is the weirdest eating craze going on out there, either). I have found ways to avoid discussing my digestive condition over dinner (hello, people, MANNERS??), and you'll find things you're comfortable saying that effectively end a conversation you don't want to have. Sometimes just looking a rude person in the eye, with a pleasantly expectant smile, will do the trick - you're waiting for *them* to explain why they have some opinion displayed on their face, not trying to convince them of something you don't honestly care whether they accept or not.
You don't owe anyone an explanation, but if you choose to offer one, I recommend oversimplifying

That gives the impertinent an opportunity to drift back to their real favorite subject - themselves...
I can also see how it might take a couple of runs at it to be sure that GF (and everything-else-F) is for life. My gluten 'crash' was so severe, it was very persuasive, but that's not true for everyone.
I used to skip a lot of stuff on cookie trays, back before MC, because sweets are not my biggest craving, and most cookies only tasted "OK" to me (and I prefer to eat "awesome"). Let me tell you, not eating cookies for any reason makes some people crazy. I shared an office with a fellow years ago who would get angry at me for not eating sweets I didn't want, because I was not overweight, and "could afford it." So the food-rudeness and insanity out there is free-floating, and probably happens even when we're not in the room to give it a focal point.
Oops, pet peeve alert!
Sara