Small town problems!

And even if that’s what the OP thinks, messaging the organiser to tell her she’s not now coming because boring Doris is is a deeply weird thing to do. Why would a total stranger care about the OP’s existing friendships and identity crises?

OP, why not just move to a city? DS’s second primary was in the city centre and the school run regularly featured parents wearing anything from circus costumes to medical scrubs, and my drinking gang are people I met there, and include a housewife, an artist, an architect, a musician, a guy who does front of house in a restaurant, a guy who does energy retrofitting, and an archivist who wears incredibly beautiful clothes.

Or the alternative 'persona' could be a fetish/swingers thing and the OP is worried it will be weird if someone she knows is there. Of course it could be both....

This is odd and maybe why you don't sociaise well or have many friends, you also behaved like a teenager edging out a friend from "the group" go don't go but messaging an other adult because you don"t want a "friend" going is weird.

I think if you try living more authentically, while also appreciating people for who they are, these problems will solve themselves.

You want to offload an existing friend because she isn't the sort of 'party person' you aspire to mix with. You want to join a group of 'party people' in an assumed 'persona' of being a party person yourself, and don't want the other friend cramping your style?
I don't think this is going to work. Because if the only way you think these type of people will accept you is through trying to be something you're not and you feel association with someone else will drag you down, I don't think you've the confidence to pull it off.
Why not just join what you fancy, go, and be yourself and be polite to your other friend whilst mixing more widely, and see how you get on?

I don't understand why you messaged the organiser. Your 'friend' obviously wants to broaden her horizons too - how horrible to have someone watching her movements saying oh no boring Doris is coming, I'll scratch.

Do people actually do this? It sounds incredibly self-absorbed.

Yes, exactly! It’s not that the ‘sensible’ friend is going to be disrupting a carefully-curated group of the OP’s favourite type of party people, it will be a random bunch of people.

This. You sound terribly immature, wouldn’t a vague ‘I can no longer make it unfortunately’ have been so much better. Just seems like you’re trying to get people on side or thinking badly of your (ex) friend. Mean girls shit in a small town, that’ll soon get around 🙃

Again, that perennial Mn mystery — why have friends you don’t like? I often
feel like some kind of radical on here, purely because I like all my friends. If I didn’t, I wouldn’t befriend them.

OP, it isn’t necessary to completely reinvent yourself for each friendship context. Sure, different friendships bring out different parts of us, but I have, for instance, a younger friend who spent Christmas Day doing magic mushrooms with her parents and siblings, and a friend who used to be a nun in an enclosed order.

I don’t morph from being a hallucinogenic-fuelled hippy to being an observant Catholic as I move between them. And I’ve introduced them to one another by having them both round to dinner and they got on really well!

You can’t tell someone not to go to an event organised by someone else. Grossly self absorbed behaviour.

Its absolutely none of your business.

Or just pretty ordinary people meeting up for a bit of a fun evening.

No, it’s the kind of thing teenagers do when they’re trying on identities. Usually by the time someone is old enough to have a ten year old, they’ve figured out how to blend their various masks, or recognised that wearing designer clothes doesn’t mean you’re someone else.

Bluntly, OP, focus on yourself. You can’t dictate whether or not your friend attends this meet-up, just as you can’t dictate whether the other participants are going to be cool party types in designer clothes, or middle-aged alcoholics looking for drinking company.

Or are you just concerned your 'friend' will see you doing things she won't approve of, and do what? If so the friendship isn't a very real friendship.

Wanting a completely separate friend circle and appearing appear in a different persona is exactly why people move to a city

I don’t understand the ‘persona’ thing either. Surely a person does different things in different contexts, but are still themselves? So you don’t start dancing and necking the vodka at work or at the school gate, but you might in a club or at a party. You are still you, enjoying and doing different things.

I understand different friend groups in different contexts, no one thinks that is weird, surely. If this other person is ‘crossing lanes’ why should that make you uncomfortable? They might love it, they might hate it and not come again.

I have several circles of friends because whilst I have some conventional stuff I enjoy, I have some much more out there stuff which my straighter friends wouldn’t go near. I don’t feel I’m a different person in the different contexts, nor do I keep anything secret.

This isn’t criticism, by the way. I’m just fascinated by the mindset!

It's going to be a group of people and you have one friend (or soon to be exfriend?) also going. Just go, as you say small town you will be thrown together all the time, you can still talk to other people and build other friendships, you don't have to be joined at the hip with this friend/not friend. Very confusing relationship with this friend.

Your intentions are not good for starters, it one thing joining a walking group and another joining for the alcohol social side which nearly always leads to troubles within groups, you’ve already stuck your nose out by spreading your business? The organisers don’t care who you dislike and yet you described her personality etc.

Does your corporate employer know you do drugs?

Not sure what you and your husband being grown up teens and a good match has to do with it? Aside from maybe that's why you're making this a much bigger deal than it is, because that's fairly teenage behaviour?

Go, be yourself, chat to her for a few minutes then go drink/dance/take drugs/behave like a teenager or whatever it is you want to do and let her also meet some new people.

Either it'll be too much for her and she won't go again or she'll find some new friends. Or you'll decide they don't meet your standards and she'll have new friends and you won't. Or is that the worry?

Small town, tiny minds.