Do I tell the ex's wife what he's really like?

I really wouldn't. She won't believe you anyway and you'll just look more 'crazy ex' than ever. You sound like you just want to annoying your ex because he annoys you - getting into that kind of tit for tat game isn't going to help anyone, least of all your children.

If I were you I would keep communication with the ex to the bare minimum - text or email and only about the children. Don't respond to anything else and don't be drawn into arguments. Otherwise you are just giving him the satisfaction of knowing he's getting to you.

It does sound like you are too involved in all the drama too @Unknown1111

First and most obviously, stop answering the phone. Tell him to text or email you.

Secondly, stop being the middle man between him and the kids. Get them a basic nokia phone they can call/text their dad on - kid wants an expensive jacket? They need to ask dad for half.
Dad wants to cancel visit? He can call the kid/kid calls him to arrange.

The biggest ‘f you’ you can give to this man is to live a happy life unaffected by his bullshit. You are being triggered because you are reliving the injustices of his past behaviour in the here and now alongside new instances of shitty behaviour. Tell his wife or not, it won’t change the past or him and this is energy you are choosing to spend on an ex who is unworthy of your headspace.

Please choose to know your truth, the truth, and accept that others may be fooled by his good guy act or sob story but be proud that you see the real person behind the facade. Step back from his verbal contact, stop playing his games and regain your power over your own emotional wellbeing.

The best way you can "teach him a lesson" is to do as other posters have suggested. Keep contact to a minimum. Message instead of speaking on the phone. Don't rise to the bait when he pisses you off. Accept that you don't like each other.

Badmouthing him to his wife is pointless for the reasons I gave in my previous post. It won't make you feel better.

If he treats her well and they are happy, she will think you are batshit jealous. If he treats her badly, she already knows what he is and what she chooses to do with that knowledge is none of your business. Either way, she won't thank you.

Keep out of their relationship.

You are still giving him power over you, think how happy you are in your relationship and how happy you are to have got rid of him and smile at his jibes. If he refuses to pay half for the coat reply in a way the wife will see that you and your DD are very disappointed that he cannot afford it.

You give him what he wants every time. He wants the reaction, he wants you to argue, or say something snide, or look obstructive.

He's an absolute shit, but you make him happy every time you let him get to you. Grey rock him instead, and that will piss him off.

I really hope you didn't say that to your daughter though, it would have been cruel and unnecessary.

I've missed that wording from OP's post. If that's what she said that I have lost all my sympathy for her.

(I shouldn't answer I know) and start a conversation to attack me and goade me

ABD EVERY SINGLE TIME YOU TAKE THE BAIT.

You said it yourself.

You are stuck in a hamster ball, keep acting the same and expect a different outcome.

Oh no you did not say that did you? That's awful.

You tell your children the truth. I have a 10 year old and her dad promised her holiday, then bailed. You better believe I wasn't covering for him. Why? So her face dropped. You can't shield them from like, they are going to be disappointed and let down multiple times. Don't even think about messaging new wife, you will be a laughing stock and a common enemy, she will not believe you. You don't have to answer his phone calls. I had very hostile break up, my ex cheated, but now I have absolutely zero feelings for him, complete indifference, I wish him well tho. You on the other hand are consumed by your former relationship, I don't think you WANT to let go. Your girls at 10 and 12 know a lot more than you give them credit for. You have to let go before you ruin your marriage, as your ex is living in your head rent free. I couldn't be with a partner like that

You will look like a crazy you know what if you do that.
Just sit tight, be the bigger person, and in the long run, his new wife and both of your girls will realise what he is like. Don't stoop to his level.

Omg pls tell me you didn't say to your child that her dad doesn't want her ffs. That bloody unhinged and cruel. You could have easily told her the truth without sounding like a bitter ex

Bloody hell.p, I’m sorry, OP. Did you have a good lawyer? You could have had both.

I told my DD who is ill and her bday weekend to celebrate with dad that dad said as your ill he doesn't want his family to get ill so he doesn't want you: and her face dropped. I can't do that to them

He doesn't want you

That was unnecessarily cruel wording if I'm honest.

Don't stoop to his level or you'll both end up fucking up your kid's mental health.

I agree you definitely should be honest about their dad, but please do watch the wording in future.

You need to take back the control he still has over you. You know you have an emotional response when you speak to him, so stop answering his calls. And stop trying to protect the kids from what he's like as I think that'll do them more harm in the long run.
He's clearly playing games based on the they can come/ can't come situation so play it better. Something along the lines of 'Dad says you won't be able to visit this weekend. That might change again though so let's get your bag ready either way' maybe. Allow a child appropriate level of seeing how unreliable he is rather than you needing to fabricate explanations for him every time.
They deserve to fully understand that the have a shit dad.

we started a business together which he is director of and it makes millions

Did he get the business in the divorce?

As others have said, don’t answer his calls - text or email only.
Don’t rise to his criticism.

depending on the age of your child, can you explain ref the coat that you have transferred your half into their account to buy it, they now need to ask Dad to sort his. Keep it friendly, don’t slag him off. Just state facts, you’ve transferred, now he needs to.
If he calls you about it, ignore it. Text back with ‘can’t talk now, is everything ok’. If he moans about being asked ref the coat money, just ignore him, that is his problem, not yours.

I wouldn’t be answering any calls from him. There was someone on here posting about their ex not too long ago, and their standard reply was something like ‘let me know how that works out’ (others can probably remember it exactly) and I thought it was a great reply.

Unless it’s to do with your children you don’t need to listen to him.

I can imagine how unfair it all feels, I hate people who re write history to suit themselves and really struggle not to stick up for myself and correct them, but some people won’t listen so it changes nothing.

Why are you arguing with him? You say you know if his wife heard your conversations or saw your texts she would think you are 'a crazy bitch'. So in fairness, you are being. The only way to take control back from him is not to argue. Don't rise to it. Calmly state facts. He is trying to make you angry. So don't let him. That's the only way to win.

I like the suggestion around the coat example - tell your daughter the truth. You don't have to get angry or slag him off. If he comes back for you complaining, then just calmly explain facts again - you did say you would pay for half the coat, you are now saying you won't. Once you pay me half as agreed I'll buy it for her. Hopefully your DDs will start to figure it out for themselves - ie he can't afford £50 but yet drives a beamer/goes on luxury holidays/eats out all the time, or whatever his lifestyle involves

Oh OP, I feel this deeply, I have suffered from post separation abuse. There are loads of good resources out there on how to deal with this but it's so hard!

Perhaps not saying anything then - does your DD have a phone? If he doesn't turn up she can phone him and ask why, just tell him to contact DD direct if he's not coming and then ignore.