What rude and horrible people!

It sounds like you have it sorted though. Only big family events and your dh says that he doesn't mind if you don't even go to those.

i know what you mean about wanting to protect your children. It's only natural😀.

Do the sisters like your dh? Are they nice to him? It all sounds just horrible 😧.

DH knows all this, wants to ignore it and them as much as possible, only going to bigger family events. I’ve said I don’t want to go to any which he’s accepted and understands. I don’t really want my kids round them at all, no family is better than a passive aggressive and shit family, which is probably unreasonable. Any advice appreciated!
Hey - you & DH have absolutely got this OP. So well that you don't need advice!
This is absolutely the best strategy. Your DC will develop their own friends, maybe even with DC of your own friends.
But keep posting to vent & to get support.

‘oh what a shame we messed up the invites and you missed it, you’ll need to come to the next one'.
Have you ever batted this back at them?
"So you always say, but seeing as you do this regularly it wasn't a mess-up was it? Why not cut the crap & simply not pretend to invite me, next time? Would that save you time & embarrassment, or are you getting a sad thrill out of playing your little game?"
If you can say something like that in MiL's earshot, so much the better.
That may not work for you - but for me, I'd rather lose the infuriating bullshit & stop getting fake 'invitations'. Also let them know you have rumbled their game & don't give a shit about it.

As to the rest - the pointed failure to 'see' you as social events - just avoidiong them is the simplest strategy. Can you have PiL's round on their own, or go to theirs without your ghastly SiL's?

You and your children are better off without an extended family than hanging onto the fringes of one that excludes you. The older they get the more apparent their different status will be to your children, and it will be harmful for them.
Many people don't have extended families but build a supportive circle around them of friends and know those people are in their lives from choice, not obligation.
In your shoes I'd push these people to the periphery and invest my time in cultivating my friendships.

Sounds awful, you don't need people like that in your life. If your husbands happy to just go no contact just do that.

My view is, why would I let my kid be around someone who openly an asshole to me? My job in life is to surround DS with good role models, rounded individuals and show him that we dont have to take awful behaviour from anyone - even family.

So I'd send DH off to visit his parents on his own - and restrict it to just the big events. And on those days, you and your children do something else. After a while they'll spot it - and when they do, DH can tell them exactly why you and your children won't be around that coven any more.

Like you say, you married your DH, not his family.

They don't sound like nice people to hang around with, so don't bother to see them anymore and spend time with your friends instead.

Just because someone is a blood/legal relative, doesn't make them a nice person or someone you have to spend time with.

Focus on your friendships and if your DC ever question the lack of closeness, just explain that they were unkind and that you don't have to spend time with unkind people.

Family photos rarely include me, sometimes I get ‘forgotten’ other times they say straight out they just want family in the photos.

Um, come again? What did your husband say to this outrage? I assume he immediately told them all to go fuck themselves and defend his wife, correct?

Are the family well off? Are they concerned about where the family money will end up ?

Whatever, they sound like weird effing sisters.
I don't think you should subject yourself or your children to their bullying any longer.

Some people are arseholes, family or not.

My cousin moved next to me (I couldn't abide them and their P). Particularly put out when I informed them that one mutual set of grandparents did not a relationship make.

The best things I think you can take from your thread OP is 1) you & DH are on the same team & 2) you are remarkably clear-sighted & aware.

I hear you about not going down the confrontation route. May be an arseache too far. But you can daydream about the satisfaction, laugh about it with DH, & ... keep it up your sleeve as the nuclear option if, one day, you have had enough & feel like burning some boats

for the email thing, next time one comes, just keep replying to it, reply to all, and say you seem to be missing details, so at least they know you know what they're up to

I've thought of doing something like this but one of the SILs is particularly vile when challenged and I'm worried it would bring all this background behaviour to the foreground and they'd all back her as they don't want her nastiness directed at them

What have you got to lose? I'm really gobby and confident so i'd just tell them that school was over years ago and they can stop being the mean-girls and fuck themselves.
But you need a strong stomach for that (3 of my SIL just ignore me now since i did something similar. It has not had an adverse impact on my life )

bless you. its them. they are feckers. I personally wouldn't attend any family events but certainly invite in laws to dinner etc at yours....

They all buy great presents for each other’s kids, as do we, all spending £25-35 per child. However, 2 of the sisters have never spent over £10 on ours.

This involving children is nasty - and is set up to make yours feel second class. I would reciprocate with the kids gifts basing your purchases on what your kids received from their parents the year before. Assuming their pattern does not change they will not be able to moan given it is an 'exhange'.
Alternatively I would stop exchanging gifts in person altogether. Dump them all a 'cheap' gift at PIL ahead of time. Don't let them treat your kids as lesser.

The situation with PIL is sad. I'd ask them over to yours separately from sisters/cousins. I'd have DH explain what he has seen occurring and say that you won't take the kids to such events anymore as you do not want them being treated as outcasts and your eldest is noticing the behaviour so it is effecting them. If they want to see dc then they will need to make an effort without the rest of the family. You will see then how things go.

I think your DH has lived this all his life so doesn't see anything in it and will find it uncomfortable to extract himself from it - but if he sees the impacts on your own dc he will probably get there given time..

And I'd save the extra cash not spent on this pantomime of a family to go and visit your brother...

But you need a strong stomach for that (3 of my SIL just ignore me now since i did something similar. It has not had an adverse impact on my life )

Result!
Nice one, @Brefugee 😂😂😂

My view is, why would I let my kid be around someone who openly an asshole to me? My job in life is to surround DS with good role models, rounded individuals and show him that we don't have to take awful behaviour from anyone - even family.

This, why would you allow your children around adults who deliberately set out to hurt their Mother and it seems their Father and them by way of cheaper gifts? Go low contact now, stop trying. They have clearly defined their boundaries, time to clearly define yours.

As for your children growing up without extended family, lots of people don't have extended family. Better to surround yourself with their friends and your friends; children who actually care about them. If you don't they will soon start to notice the disparity. We did as children, I wish my parents had cut my Grandparent out of our life than feel less worthy through no fault of our own.

You are so much of a better person than any of them.

Your kids are going to grow up fine with you for a mum.

I'm sorry that this family isn't treating you well. Concentrate on building up friendships with lovely people and your children will benefit from that