to feel hurt at being left out by family members?

I was on your side there. It is ridiculous to leave one sibling out without having a conversation about it beforehand. It is just thoughtless behaviour surely.

People here have such low expectations of behaviour. From partners and friends and family.
Of course you shouldn’t leave somebody out in the family like this without any discussion!

You are clearly not close if you can’t even raise this with your family. There is no point posting online here if you don’t take any action now. Just ask them and say that you were hurt. They need to know.

No, just no.

I can completely understand why OP feels how she does.

They should have included her.

OP, I think you need to ask why not invited too and explain what you've said on the thread. You sound calm and measured so I'm sure that is how you communicate irl too.

If you want to go to something with all or your family why don't you suggest/organise it?

If you wanted to go to this event you could have-with your siblings, without them or just met at some point.

It seems to me that you showed no interest so weren't asked.

You seem more bothered that siblings did something without you than the event itself.

If they all had a shared hobby that you showed no interest in would youexpect to be invited to related things?

You seem determined to find offence where there probably is none!

Why do you feel like you needed to be “invited”? You knew your DB was going and anyone can buy tickets. If you’d actually wanted to go wouldn’t you just have got yourself tickets and gone along? Presumably your other siblings did that, rather than there being some big conspiracy to exclude you.

“I didn’t know you lot were all off to XXXfest together - why didn’t you say something?”

That’s not a big deal to ask. Followed by “How was it?”

I agree it’s hurtful to feel left out. Do you go camping, OP, do you have all the stuff? Or might they not have got the impression that camping at a festival is your thing?

There is absolutely no point in sitting feeling hurt without saying anything because that just compounds your hurt. Also, you should be able to turn around to family (particularly siblings) and say, "hang on a minute, where was my invite?" Or "why did you decide not to invite me?". If you can't say these things to family, then who can you?! Definitely bring it up, otherwise it will happen again and you will continue to feel hurt. They may be able to offer some reassurance re their thinking behind the decision.

Why. Why will it cause aggro and tension? Why can't you talk to each other? What on earth is wrong with your family dynamic that you can't say how hurt and pissed off you are that not one of your siblings thought about letting you know they were all going to an event to see if you wanted to come too.
Why should you be the only one upset? I'd be reading them the fucking riot act. I'd want an explanation and an apology even if I thought they didn't mean it and a promise that I wouldn't get left out again.
Sounds like you're not going to say anything and you're just going to pretend it doesn't matter. It's nasty behaviour at worst and thoughtless at best and you'd better get used to it happening again, in that case.

I knew my DB and his wife were going to this one. I didn't know they were taking the kids and I didn't know they'd invited the others and their families

They probably hadn’t. They may not even have mentioned it to the others until after the conversation you had. It would be very weird to ‘invite’ someone to what is a public event open to all. As pp have already suggested, it was probably that the others expressed an interest in going which you did not.
Did you say anything like ‘oh, I wouldn’t mind going to that’?

I hardly think your db would have mentioned it to you at all, if there was a plot to exclude you. Not many people would be motivated to go to an expensive event they wouldn’t otherwise have contemplated, just because certain members of their family are going. If you were to say anything, your db might take umbrage over you not being interested when you thought it was just him and his wife attending!

Instead of thinking there has been a long standing agreement that excluded you, it is very likely that tickets became available at the last minute , perhaps their friends couldn't go so they mentioned it to the others. Often happens with events where the tickets have to be bought well in advance.

They have already caused an issue by leaving you out.

OP why don't you jusy say next time they all do something together, you would like to be included even if they may think it's not your thing.

That way you are not being confrontational yet have made your position clear. So next time they leave you out, you know they are a little crap and will lower your expectations going forward

But you weren’t interested in going at that point. You only got interested in this festival when you discovered all your siblings had gone. That doesn’t make a lot of sense to me. If I wanted to go to something, I’d get tickets. I wouldn’t suddenly get interested in an event based on solely on who else was going.

What did you say when your DB mentioned it? You say you assumed they were going with friends or on their own, did you not ask them anything about it?

I think you need to be careful what you say to the group, depending on what the conversation with your DB was like, I mean this kindly, but you're bordering on playing the victim here by saying they didn't specifically 'invite' you and your feeling are hurt by them excluding you.. you honestly don't 'invite' people to come with you to these things, you mention it and if someone shows an interest you make plans to meet up there or go together.

This is how it would normally go:

DB: we're going to 'event' in a few weeks.
YOU: sounds great, who's playing?
DB 'band name' are headlining this year.
YOU: I've never been to 'event' but always thought about going.
DB: Why don't you come? I've already asked sibling X if they want to go, if they say yes, we could all make a weekend of it!

VS

DB: we're going to 'event' in a few weeks.
YOU: that's nice, hope you have fun, changes subject.

DB then has the same conversation with your sibling in which they express wanting to go so they make plans, they may have asked about you, but DB would then say "I've already mentioned it but they didn't seem that interested".

Only you know how the conversation went OP, if they don't have form for purposely excluding you It really could just be a simple miscommunication/misunderstanding.

I'd say something along the lines of, "your pics from 'event' looks great, I wish I knew you were all going as I'd have liked to have come along too", no need to accuse anyone of anything but it may make them realise you're a little unhappy about being overlooked.

Or, @user092521 , you could find a way to have a conversation with them about how it makes you feel, without being combative, and they can reassure you and promise to be more inclusive in future - and your relationships may actually be improved. Give it a try 🩷

I would be hurt too.

I'd assume it happened organically - one booked, other liked the sound of it and booked too. As opposed to deliberately excluding you.

You have three options-

1, Mention it looked fun, if they do something like that again you would love to go. This is my favourite as you're not being negative but making the point you want to be included.

2, say/do nothing

3, tell them your hurt. It's valid but runs the risk of making them feel defensive and creating bad feeling.

The only thing you can do then is tell them you feel hurt and ask why you weren’t invited.

I'd be hurt too. I think you need to raise it so you're not pondering it.

But if you wanted to go, why did you not express an interest, or make plans to go with your sibling and his wife when you heard they were going (like your other siblings probably did).

YANBU to be hurt, but it sounds like you would not have gone anyway. They very likely knew you wouldn't be arsed.

Would have been nice to have been asked I guess - but I don't feel they have left you out to be mean and spiteful.

Mention to them (breezily) in passing, that you'd have quite liked to have gone, and if something similar comes up again, can they ask you.