To feel sad what my 10 year old said to me

Absolutely not! 10 is old enough to understand hurtful.comments and when someone is upset. There needs to be consequences here.

The first thing that jumped out at me was that you haven’t had any new clothes for 5 years. You’re clearly not so short of money that you can’t afford them, the incident happened after you’d been on a family cinema trip and while you were. out in a restaurant . The fact that you’d put on weight due to having children would be a reason to buy new clothes, not to keep wearing the same ones that don’t fit. So why are you so low on the family priority list?
Is DH controlling your spending, is it you thinking you’re not worth it?
It sounds like DH is not supporting you and that DD is spoiled. You are worth so much more than this, but if you don’t respect yourself and allow people to treat you this way, they will continue to do so. It is very hurtful to have your DD talk to you like that, and more so for DH not to back you up.
You’re not doing DD any favours to let her talk like this. Time to toughen up, withdraw privileges and make sure she knows why. If you are denying yourself decent clothes in order to indulge her, that needs to stop. You need to demonstrate that you value yourself.
If the new clothes have been ruined for you, send them back and get some different ones. Take a day out going shopping and trying on.
Tell DH his lack of respect diminishes him, and that you expect him to support you. Start thinking about how you can reclaim your self esteem.

You and your husband need to be united here. It's very concerning that he laughed along with her so you may have a husband issue as well as a daughter issue.
Anyway, get him to WFH for a day while you take younger DC to London or wherever. Give her a horrible task to do for the entire day (cleaning, maths practice, watching Question Time...) and make sure your DH is on board with enforcing the punishment.

I have a ten year old girl and she would simply never.

I feel for you so much, OP. I am carrying excess weight that I just can’t get rid of and it drags me down every single day. I find myself not wanting to go out because of it. No clothes look nice on me. I don’t really have any advice for you but you’re not alone x

Oh, and you need to sit your DH down and get him onboard.

I would sit her down and talk to her about it, about using respectful language and about how talking like that will get her in to trouble at home and school.
I would then ‘ban’ the word fat when it comes to people. She’s not to use that word about you OR anyone else and give her consequences for doing so.

She needs consequences OP. Your husband needs to know laughing along with her is wrong. You both need to sit down with her and explain how unacceptable her behaviour is. She needs to apologise and be punished. I would have made her and DH stay home whilst you and the youngest had a nice day - something like that. Good luck OP.

The child in question is a bit of a gobshite tbf

Tbh the person I'm sorry for is the blameless younger child who has been punished by missing out on a holiday treat because of their parents' inability to teach their older sibling how to behave.

I have so many feelings about this situation but I will hold my tongue except to say I am very sorry this happened to you.

No, it doesn't sound like that. It sounded like a continuous, vicious targeting of her mother, mocking her appearance. This continued later, and included rudeness about the mum's new clothes.
This is more than "Yo Momma" or humorous "roasting". This is a 10 year old girl who, on a family outing, instead of engaging positively attempts to humiliate and denigrate her own mother.
How it's got this bad is something that the parents need to deal with.

It is the "Yo Momma jokes" she has heard them in school, they're popular among 10 year olds.
They are all over the Internet
"Yor Momma is so ugly she blah blah" or "Yor Momma is so fat she blah blah".
I'm not excusing DD, she took it too far but it is a popular skit for roasting among children of her age.
She didn't make it up herself.

DS had said it to me in the accent, I told him it was rude, I'm not overweight so didn't give it much thought afterwards.

My marriage would be over too. I’d be leaving the 10 year old with DH for the Easter holidays, taking the youngest on holiday and seeing a solicitor to start divorce proceedings.

Do you tell people at work and in the community that they’re so fat and ugly they break all the mirrors? If an adult said that at work they would be disciplined, if not sacked immediately for gross misconduct. If it was said in my town they’d be roasted right back.

Exactly.I don't get the fear of children these days. Children forget and they would do well to remember that they live by the grace of you. Without you they get nothing.

They are dependent, meaning they need you to buy them stuff.They behave like nasty little brats, they get nothing. Why is that so hard for parents to do?It's all pandering and gentle parenting and softly softly will look what its done.

I’d be pre-warning her now that all her Easter eggs are going to a food bank if this behaviour is repeated.

No new clothes except school uniform and PE kit if she continues to be unkind.

Also, tell her you’ll wear whatever you like as a grown adult spending your own money on clothes.

Removal of electronic devices.
Missing out on trips out that your younger child still gets to enjoy.
Separation from your DH if he continues to reinforce this behaviour.

Talk to her about being kind and why it’s important. Tell her if she continues with this behaviour, there will be a consequence. Make sure DH is on board and ensure the consequence happens. I had a banter-type relationship with my DD when she was younger (would never have put up with what you describe, though).

In recent years as an adult she has been downright insulting at times and it has been painful putting boundaries in place. I wish I had nipped it in the bud when she was younger. People will behave according to what you teach them you will tolerate.

honestly id be buying a one way ticket and starting a new life somewhere else. Id leave a note to say “mummies so fat and ugly so she’s disappeared” but that’s just me!

Absolutely! This child is a proper little brat and her parents need to clamp down on her now!! Then they need to refine their parenting skills!

Completely wrong. This has nothing to do with anyone being perfect or not perfect.

The rudeness should have been nipped in the bud from the outset. Instead both parents have validated- husband by laughing and OP by taking the comments to heart and acting upon them by buying new clothes.

The FIRST time she said it, I’d have come down on her like a ton of bricks. No way would she have been allowed to say it more than once! A short sharp lesson in manners would have been delivered. You’re the parent - she needs some strong consequences.

My answer would be "Are you perfect? Think about it and don't come back when you really are.
Wish you strength.

OP, I’ve already posted about your DD’s behaviour but try not let this destroy your confidence about how you look. The world is full of over-weight people and they can still look and dress well. I see over-weight people all the time and yes, they could do with dropping weight but my first thought would be, I like their outfit shoes, etc, rather than their body shape. I don’t think most people go around thinking oh that person is overweight because in reality, we couldn’t care less. Good manners and being friendly is much more important. If you feel good in what you’re wearing you will have a spring in your step as such, so wear your new clothes with pride.

So, ditch the leggings and tunics, wear your new wide leg trousers. Nice shoes/trainers and a bag, jewellery, whatever. Take an afternoon to go shopping by yourself, even if you don’t buy anything, try on lots to see which shapes/lengths/colours etc suit you best and it will make online/future shopping easier.

Don’t make any reference, excuses or apologies to anyone about your body shape. If you want to diet, then do it for yourself not because a 10 year old has called you fat.

If you’re in the trap of spending most of your budget on clothes and activities and stuff for yourself children, leaving nothing for yourself, get yourself out of that trap. Most of our children have far too many clothes and you deserve nice clothes as much as your children. Let your DD see you have your own life too by taking time out by yourself to go shopping, meet up with a friend for a coffee, get yourself nails done or whatever. Find yourself a hobby. Take an hour by yourself in the evening to go for a walk

I hope you are feeling better about things today.

Sorry but your daughter is a bully (ignore the excuse of it's only roasting/banter) and your husband is an enabler. Let both know how disappointed and hurt you are. Keep your new clothes and work on your self esteem.