I do understand, twinlolly, food intolerance and differing beliefs about eating animal products are a minefield sometimes. You’re right, a vegetarian will rarely prepare a meat dish. I understand as it conflicts with their beliefs. A friend simply refuses to have any meat or meat product in her cooking pans, I respect her beliefs and choices in her own home. She has to tolerate me cooking her food in pans that have been used for meat when she eats with us.
Personally I’d happily eat a vegetarian meal as I enjoy the food, my husband dislikes most but eats it out of politeness if we’re served it by a friend. I can feel very anxious if I need to cook a vegetarian meal for guests in the same way I feel anxiety about cooking for someone with severe allergies. Yes, I do cook separately for vegetarians out of politeness as long as I know in advance. Sprung on me on arrival I’m afraid they will need to pick from what is on offer,
My go to is a vegetarian version of a very simple main course served alongside a meat version for the meat eaters. Cottage pie, curry, chilli, lasagne or in the summer often a flan and salad with new potatoes. A cousin is vegetarian, she always tells me to give her supermarket ready prepared food, not to stress or struggle because of her, sometimes I listen, often I don’t.
As you have had a bad experience of vegetarian food why not ask a friend who invites you what they plan to serve. If you think you’d not be able to eat it explain kindly and offer to take your own meat containing food to re-heat. Our lactose intolerant family member always brings her own milk and anything else I’m not likely to have, in my view it’s little different.
You do sound stressed about it, hopefully you can find a way through and keep your good friends, it would be a shame to miss out on their company.