... I'm only going to be able to host once a month. She said this was fine, so I'm clear for awhile.
This speaks volumes to me - How kind
of her to give her permission for you to determine how often you'll be hosting in your own home!
I don't have a lot of patience for people who self-prescribe strict diets. I am willing to make sure that I have an offering available to them, or leave things separate so guests can add things or not (leave the nuts out for allergies, or make sure I've got ham AND roast beef on offer for make-your-own-sandwich if someone with religious restrictions is visiting).
When I'm on crazy fad weight loss diet I bring my own food, or select from what I can clearly see (without asking!) is allowed - usually from the raw veggie tray.
At first I looked through your friend's reactions with that "dieting is hard" lens, how awful it would be to be told "never again" for so many favorites when diagnosed with diabetes and how that could be emotional, but she totally lost me, as I said, with the above quote.