to ask how to deal with family criticism over sending our child to a private school?

What utter nonsense.
All the while you earn the money op, it’s your choice. I would literally just look at them blankly. If they continue I would ask why on earth they feel entitled to dictate how you spend your own money. Did they approve the house you bought, your car? Perhaps attend job interviews with you to ensure the company is suitable? No? Then they can back off. We live in a democracy and thank god for that. Private Schooling, Private Health and anything else you can pay to hopefully improve is part of that. And I say that as someone who was state educated and same for my DC.

They have called you “cruel”

FGS you and your DH need to woman / man up

My inlaws were like that. Kept dropping in little snarky comments and digs about our choice to go private. I had to bite my tongue so many times as actually they were both very poorly educated and without any qualifications, and my DH initially had left a similarly shit school that they had been to and was the main driver in I want the kids private.
Fortunately they lived a long way away from us and my husband just cooled on the visits for a few years.

Haha what a load of guff.

How on earth are they totally isolated when they (usually) do extra curricular sporting etc activities outside of school with children from all backgrounds, spend time with family from all financial backgrounds and can be (as in my case) brought up by state educated parents?

God knows who you are meeting.

The threads on here about the significant issues with state education are eye-opening. No thanks.

Exactly....those being critical don't take into consideration that what they say is out of line, can cause upset and none of their business.

Why do people that give their unasked for opinions get all offended and take umpage when the receiver bats the same treatment back.

It’s definitely not acceptable OP. They have over stepped the mark multiple times and have been very rude

But they are also not entirely incorrect that there is a risk that your DC will inculcate objectionable views about poorer people during an elite education. Could you try to reassure them with examples of how you’re handling that risk alongside providing the schooling that you think is absolutely the right fit for her? I know you shouldn’t really have to do that, but maybe it might help shut them up?

You say you’re tempted to tell them that if they carry on, then you’ll stop seeing them but you feel it’s too extreme….

but then you say your husband has already firmly said this anyway and it’s made zero difference

Jesus Christ! Incredible. The cheek. And in fact the rudeness. It's absolutely none of their business and if you ask their opinion they can give it. Otherwise. No.

You are going to HAVE to tell them to stop. You're going to have to make a stand. Properly. Because this is an invasion of your privacy and is totally out of order. You can't let them continue to intrude in this way

Just keep repeating that the decision has been made. And your daughter is looking forward to it. Thank you.
they’ll get over it presumably with time

It would be entirely their parents fault

Every parent should be striving to do the absolute best for their children. You must have reasons for going private (we did, our state options were dire)

I’d not hesitate to see them less if they won’t give it up. Bring up something they do that irritates you as a counter complaint every time, that might stop them!

I get what you are saying but how do children in other countries do well when private schools aren’t a big thing . It’s not really anything to brag about. I’m not criticising by the way as maybe if I lived in England I’d send my DC to a private school as well

That the privately educated DC will eventually think less of, or patronise, her state educated cousins. Or that entire side of the family. It’s no doubt unfounded, but I bet that it sits underneath it.

I’m in my forties and the other day someone gave me a high 5 at a work event because they found out I went to a comp. (My sector is highly privately educated) I do not agree with private education partly because it produces the sort of people who do this.

feel better now?
if I was the OP I would be feeling that cold stilleto between my ribs

Absolutely this.

the other option is give them a warning that you will leave if they bring this up again, and then when they do @RunBeforeBreakfast you cut the visit short, get in car, leave.

Your husband has spoken to them. I assume it's your PIL... Is there another sibling who can't afford to send their child and it's jealousy? My in laws were always criticising my decision to return to work (as kids then went to nursery), even said how badly it would affect them and how much better their daughters kids would do in life as she didn't work. I just ignored it. We are 20 years down the track and guess what.. Funnily enough they have forgotten all the nasty comments they made and my kids all did very well.
As others have said you need to agree to disagree or reduce contact? We only went to see them occasionally for short bursts to reduce the negative comments they made to my children. You will need to watch for the sly snide remarks from September to protect your daughter

. It damages them for life. They know a lot but understand very little. I see this daily in my line of work.

this made me chuckle. What nonsense

Social isolation? Oh don’t be silly

I was privately educated 4-18.

very broad range of friends and colleagues

This!

Weirdos. What on earth do they hope to achieve?
A member of DH's family educated their DC privately. I don't really approve of it, and couldn't afford it even if I did. However, their choices are fuck all to do with me or anyone else in the family. I would tell them to do one if any of them tried telling me how to run my life.

Mostly - but importantly I do not believe in this case it is a better service. I believe it does a massive disservice to the children who go through it. They statistically obtain better grades but with it they absorb total isolation from the society they actually live in. It damages them for life. They know a lot but understand very little. I see this daily in my line of work.

None of that, though, has anything to do with OP’s issue.

they have taken a parenting decision regarding their child

Invite them to speech day and crack on.