@Dinnertext I’d be really taken aback too, OP. Not because she had an upset stomach, that happens, but because of how she chose to communicate it.
Accidentally sending a bitchy message is one thing. It happens. But doubling down with no apology, implying your ingredients aren’t “up to their usual standard”, and then suggesting they only come for drinks (with their own snacks!) is… well, it’s not great manners. Any decent person would have valued your feelings and would have said they over indulged as you do when someone goes to the effort of making a meal for you and suffered for it the next day. Instead she doubled down and made it clear your cooking and ingredients were sub standard - because this is exactly what she was saying. So yes, You’re absolutely allowed to feel hurt. Suggesting they brought snacks instead magnifies the insult. You put effort into hosting, you’ve fed them before without issue, and you’re not serving mystery meat from a back alley.
If she genuinely thought she’d been ill from the food, the polite thing would have been to mention it at the time or decline the next invite, not gossiping to others and making a snide joke about needing Pepto.
Her follow‑up message reads more like someone scrambling to justify an embarrassing mistake than someone being honest and considerate. If you don’t feel comfortable hosting now, that’s completely reasonable. A simple, message would be enough and if you are sure you want nothing to do with her say something along these lines:
“Thanks for explaining. I’m sorry you were unwell, but the mean comment, effectively talking behind my back and your explanation (without apology) come across as hurtful, and not something a genuine friend would do. You clearly find my hosting below your standard, I find your friendship values/etiquette below mine. I think it’s probably best we pass on Saturday. Maybe our husbands can go out for a catchup drink another day, which they can arrange if they want”
That keeps your dignity, and makes it clear you’re not happy to be spoken about like that. Your DH needs to understand that its you she is attacking as presumably you did the shopping and cooking and he should be recognising this.
Your DH can always meet her husband for a drink another day if he wants to avoid awkwardness.
You’re not being precious. You’re responding to someone who was rude, then didn’t apologise, and then implied your food hygiene is questionable because you don’t shop at Waitrose. Anyone would feel stung and friends like that you can do without.