To have nothing further to do with them?

To be honest, the not-knowing why would do my head in, and if I was going to ‘go nuclear’ I’d just ask them to their face what the deal is..

i think you're completely over reacting here.
im an only child from a small family. me, parents, 2 cousins (sisters) and their parents.
growing up i saw them on either christmas eve or boxing day. potentially on my mums birthday, as they are her brothers kids.
never thought to invite them birthdays nor did they come to mine.
we loved seeing each other when we did but just because someone is family doesnt automatically mean they should be invited to everything.
as an adult now, ive seen both of them the last time 5 years ago at my mums wedding. the slightly older one is getting married next month and ill see them both then.
my daughter has cousins from her dads side. she sees them twice a month at grandparents house. one is 2 weeks younger so completely the same age, they still dont get an invite for each others birthday things.

Could be. She could also be a good mother who listens to who her kid wants at his party.

But the boxing day thing is very odd.

Thanks I must have missed this comment.
Though what car do they have? I have a small car and can fit 4 adults and a child in a car seat in? You do need to plan logistically who sits where but it is doable.

OP you sound rejection sensitive which can be part of being neurodivergent that many NT people won’t be able to understand. They won’t get how much rejection you had to put up with before going nuclear becomes the safer option. I totally understand your reasons for walking away. It really hurts when you read of all the wonderful family relationships that are formed thro marriage and yours resembles nothing like that.

I don’t have the Disney SIL either. To be fair my brother has had so many wives now I barely get to know their names but in this I also learned the fuck em attitude much sooner.

Have you ever asked them what the problem is? I know easier said than done but it will make them far more uncomfortable than you in the long run.

Dont go all woe is me, see it as a lucky escape and work on developing local friendships for your child. These will follow her through school if she’s lucky.

I think you need to build your self esteem and stop placing so much emphasis on the approval and acceptance
of people who sound like self centred arseholes. (Not seeing a sibling is one thing ignoring their own parents? That’s another level)

feel free with the no contact and teach your child the rejection resilience you probably didn’t get the opportunity to learn in childhood.

AHH sorry I still stand by her not being a good daughter, sister, auntie.

Is she ashamed of them for some reason? My friends sister is an awful snob has cut off all but a very wealthy uncle 🙄

Based on the OP I'm not surprised that they're being excluded.

My kids’ cousin had a little family tea at the weekend this year (that we were invited to) and then a party on their actual birthday for some local friends. I was a bit hurt to be honest because the cousins are very close, but I wasn’t going to pick a fight over it. I think they have put your child in the family box rather than the friends box.

Rather than go nuclear, just stop back, stop making so much effort and see how things turn out. Maybe you were coming on a bit strong?

Some PP are saying what a ridiculous fuss about a birthday party. But the party was the last straw. The rellies had been doing the slow fade for many, many months. Or, it doesn't actually sound like a slow fade, it sounds like they were cut out pretty brutally, suddenly saying no to everything.

When people you have previously been close to just drop you, instead of telling you what the issue is, it's rude and immature. Not to mention really, really insulting. Also hardly practical considering they are family.

I doubt that it's come from the other DC, otherwise they wouldn't have let the cat out of the bag.

Either OP has done something, in which case these supposed adults should communicate with her, or the adults are envious of something about OP's lifestyle, or there's something about OP and/or her family that they don't like. I'm wondering if it's political differences, in these divisive times?

They are saying it. They're just not using words.

OP has picked up on their pulling back and it's made her pursue a smothering relationship even more.

SIL knew OP would go nuclear about their kid having a birthday party and not inviting OP's kid. That's why they kept it secret. They don't want to deal with her having a tantrum because she didn't get her way.

OP certainly feels rejection strongly and has issues from her past. But that doesn't mean she can ignore another kid's parent's no. She has to look at her own behaviour and work on that.

I expect they told everyone not to mention it and didn't share photos as they knew how you would react.
Would you have felt any better had they mentioned beforehand that they were having a party but your DS wasn't invited? You probably would have still been posting then about them excluding you and not letting him join in. I imagine they know how you react to situations, hence trying to keep a distance now.
Maybe the cousins aren't quite as close as you think. I know my kids and their cousin love seeing each other at first but after an hour or so they annoy each other and then don't want to be with them and ask to go home.

Read the OP’s updates, the PILs are too big to have more than one adult in the back with the DD’s car seat.

How would your ND DD get on at a busy party where she didn’t know anyone apart from the birthday child, who would be busy with all their guests, not just your DD?

Why can't you get in the car? Surely DH drives, then one adult in the front, two adults in the back and the child in the middle?

I think it's the OP's DH's sister, so the BIL isn't the one related to the grandparents.

Your taking this far too personally because of your own issues of being an only child and have tried to push this more than they want.

I don’t know.
we've always had the organisation you describe: one b’day party with friends, one with family.
We had some ‘joint’ parties but it quickly fizzled out. Children don’t know each other. It just doesn’t flow as well.

I really wouldn’t take it as a sign that they dint want to have anything to do with you etc….

Also I’m an only child too. (One reason why I have 2 DCs…). SIL+BIL have 3 dcs.
Weve never been very close. SIL and I never ‘jelled’. Dh doesn’t get on with his sister. So the cousins saw each other only occasionally a few times a year,
They are all adults now. Dc1 is planning a hols next year with two of the cousins.
dc2 has gone away with two of cousins last year too.
All that say that not seeing his cousin often as a child doesn’t mean your dc and his cousin won’t be close as adult.

Well your BIL can't be assed to see his parents more than twice a year so grandparents don't see their grandchild. I'd say he's neither a good son, brother, nor uncle.

Supposed to love them is an odd phrase. 'Love' isn't duty in the way you see it. It doesn't come automatically with blood. And if 'like' isn't even there, then it's no surprise they'd rather go their own way.

Boxing day is mad though, I'd be having words with your husband about that.

It's the way of the world that you get on with some people more than others. Would it be worth speaking to a counsellor about why this incident has been so hurtful to you and caused such a strong reaction? It does seem extreme.

However, I do find the orphan scenario odd. I'm surprised that they've nominated your family given the strained relationship.

I think all families are different. For some, the cousin relationships are sacred and for others they don't mean very much at all (that's the case in my family growing up and although my kids are friends with their cousins they aren't like blood brothers).

It's absolutely fine to have a different view on it. Your view is that family should be prioritised at every birthday. I disagree. Op's view is more like yours, maybe her in-laws views are more like mine.

What isn't ok is going nuclear and blocking everyone. That's very dysfunctional and although you're trying to be nice to op, I wonder how helpful you and others making these sorts of comments are really being in the long run.

I don't understand why people are being so arsey to you, OP - except that the first reply often sets the tone.

If I'd lived closer to my son's cousins, then of course there would have been mutual invitations to birthday parties (the ones of similar ages, not the ones 20 years older!).

It's like they've got a two tier thing going on - the grandparents and family v 'people we like'. Is it not normal to have family and friends all around for the birthday (unless the GP don't want to be there)?

I don’t see why your DH can’t drive his parents in their car and you drive DD to SIL’s. The fact that you’re excluded from a family Christmas gathering is pretty unpleasant, unless you’re happy not to go, of course.

You may have said this already, but are your parents still around? You haven’t mentioned them IIRC.