To have advised friend to not mention affair?

Never bad mouth kids parents to them. They'll work it out for themselves. Be the good guy.

Re your friends situation:

As a married person with no prospect of work and a child under school age, she will be entitled to more of ex's assets than someone with a career tbh. Including a proportion of his pension, a good proportion of income for maintenance, and a larger share of profit from property or even potentially to insist the house is not sold until youngest is 18.

She needs good legal advice and quick, and probably to request mediation to agree a fair settlement.
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Tell the truth, but do it sensitively. Children aren’t stupid, they work it out.

I think you've raised a good point that DAD needs to be the one to tell the kids, with both parents present; he needs to be the one to explain and field the questions. hes the one that's started this and he needs to have the responsibility to deal with it and that includes communications to the children.

In reality the message needs to be that dad is making the choice (fact) he wants to be with someone else (fact) and is leaving the family unit (consequence). There's not bad mouthing - that's fact and consequence. Stick to fact and consequence; those are undisputed.

If he starts with stuff such as "mum never did X" so that made me leave" - that's blame - needs to stay a whole lot away from that place.

If she doesn't tell them the truth, the kids will blame HER. Kids have a tendency to lash out at the person closest to them and idolise the parent who is away a lot. She doesn't need to tell them he's an arsehole. But she can tell them that "daddy has decided he no longer wants to be married and has found another woman he wants to be with. We both still love you and he will always be your father" or something ever milder.

But I would not hide the truth and give him the opportunity to tell them himself and manipulate the kids.

but what is the alternative? even if you don't (as i don't think anyone should) but a 12 year old will hear that.
And you simply can't discount the dad spinning some line to the kids that make mum out to be the bad guy but they have to live with her because she's mum.

IMO it is better for both parents to get ahead of everything and tell them together.

yabu

Ideally mum and dad should tell the kids together. “Dad has decided to live in a house separately, dad still loves you kids very much”. When the kids ask why, dad should explain factually that he loves the children and that love is forever, but sometimes grown ups don’t stay in love and dad no longer loves mummy and dad wants to live with his new girlfriend.

It sounds as if they are moving in together straight away, and the 13 yo will figure it out immediately if daddy is with another woman when she goes to visit. Why should the 13 yo have to listen to lies about a mutual separation? It will just breach trust even more and make healing harder.

The 3 yo won’t really take it in - will just want to know that daddy will see them at the weekends sometimes (as dad works away a lot, perhaps not much change there!)

The 6 yo will need some help to process what’s happening but ImE if you can avoid acrimony will recover. It’s the teenager I’d be most worried about and will need really special and probably separate conversation.

Relatio had this exact scenario. After a protracted and vicious divorce, she came away with the house, half his Forces pension and £100,000. Don't let your friend agree to anything without a solicitor.

Ideally tell the children together. But Daddy is moving out to live with another woman. Eventually he will have a house and they can go and stay.

Don't slag him off to the children, however distraught friend is. It can have the opposite effect to what you would expect. Kids think, "She's being very nasty about Daddy. No wonder he left."

Been there. Mine were about 3 and 5. He intended to move in with OW pretty much straightaway and I refused to take any element of "blame" so we sat together and I made him say that he wanted to live with another lady and you can't live with two. At the time they were weirdly ok but a decade on their feelings are changing and they regularly express a feeling that he chose her over them (he moved a distance away). As they are now adolescents and starting to explore relationships they are angrier with him now than they were back then. He of course, when he agrees to talk about it at all (he usually shuts them down) runs the Script about being unhappy for ages etc. I tend to say that we each have our own versions and that a lot of time has passed and their relationship with him is not really my business any more. If they choose not to see him they are now of an age to do so. As the kids involved here are of such different ages it is likely they will need different approaches but its crap however it goes.

I also wonder why saying, in effect if not literally "your dad prefers to live with another woman than with us" is badmouthing him.

Obviously that wouldn't be a good thing to say to your children, but i don't see why OP (or anyone else) should have to wait until the DCs work it out. And while they are with their dad, who knows what he's telling them? which is why doing it together is probably the best move, if it can be done without too much emotion.
(not least because i do prefer the idea of the mum and dad both being there to see the DCs reactions, and support them together)

It's absolutely wild to me that it's considered "badmouthing" to tell the truth. I mean, obviously you do it in an age-appropriate way and without dumping all your emotions all over it. But nobody is serving their children by lying to them.

Kids are going to ask why, and I make it an absolute rule to NEVER lie to my kids. They have all known from a very young age that if they ask me a question, they will receive a truthful answer. Again, age-appropriate.

I would say something like "Daddy has decided he wants to live with another woman." Assuming that he is a decent dad, I would reassure them that he still loves them unconditionally and would bring the conversation back around to that each time. The younger ones may well be struggling with feelings of abandonment and if their dad is a loving father, they need to be reassured of that. Obviously if he's a total deadbeat who can't be arsed with them it's wrong to tell them that he really loves them etc because that just gives them a very warped idea of what love is.

Of course they need to be told the truth as they will find out anyway. Lying never brings anything but resentment from children.

It does need to be presented in a factual, non emotional way. "Daddy has met someone and decided to live with them".

How difficult for your friend.

I am firmly on the side of truth, even when it's hard.

It needs to be age-appropriate - so different conversations may be had with each child.

Not all information needs to be given immediately.

If this arsehole has a shred of respect for his DC, he will sit down with his wife & tell his kids with her; explain that he's leaving & where he's living.

He doesn't have to say that moment about the new woman, but should shortly after.

As for the wife, it's also ok to let the DC know how sad she is, that it's tough but they will be ok.

The silly idea that women are supposed to pretend it's all fine invalidates children's feelings.

It's not fine. It's deeply painful for them & for their mother. It's ok to acknowledge this while reassuring them.

What happens with his relationship with his DC is up to him. If he is honest and present with them, it will make a huge difference, and they'll be capable of having a relationship with him, regardless of the affair / OW.

My ex lied & let down our DC over years. Two of them have no interest whatsoever in a relationship with him. The other tries a little but fundamentally has limited contact.

I was always honest from day 1 - he was abusive, I didn't speak about that but I was clear happy his inability to be a parent & in a marriage and I'd no qualms about making that clear.

For example if she’s overly emotional they might feel there’s no space for their emotions and they might grow up feeling they have to tiptoe around her when it comes to their dad.

This is absolutely true @Nicole1111 I've seen it happen. The kids are scared to approach their mum about anything they want to say or do with their dad because they are so aware of her reaction even 7/8 years down the line.

It’s ok to share facts when the children are at an age to understand those facts, it’s just about how it’s delivered. Any attempts (whether sub conscious or not) to paint him as the bad guy or any strong emotion could damage the relationship between your friend and her children. For example if she’s overly emotional they might feel there’s no space for their emotions and they might grow up feeling they have to tiptoe around her when it comes to their dad. Or if she’s very anti dad they might feel defensive of him and that their loyalty is split. I’d therefore only support sharing information if your friend is confident she’s in the best space to share it. Ultimately whenever they find out they will be able to form their own conclusions about the true character of their father, although it’s likely to take a while, so she can be safe in the knowledge that they’ll know she has been wronged and their father is of questionable character.

I wouldn't badmouth him but I would be factually accurate. Daddy is going to live with another lady but you will still see him and we both still love you.

This one. Telling a truth that the children are going to find out sooner rather than later isn't "badmouthing" their feckless father. It is the truth and pretty bland.

And if he has an issue with that, he shouldn't have cheated, should he?

Daddy loves you all very much but he doesn't love mummy any more. Why shouldn't it be clear that he's responsible? There doesn't have to be bad mouthing for there to be truth.

The kids will likely find the whole situation extremely stressful if they don't know where they'll be living. I think she needs to see if there is a way for her to stay in the house with the children, she needs to see a solicitor and they won't allow her to be left homeless and penniless with 3 kids to look after.

It's obvious isn't it

She just says “Dad and I have decided to separate. We both love you all very much. We aren’t sure of all the details of where we will be moving and when you will see us yet, but we are working on that and everything else necessary to make this as smooth as possible.”

Definitely no badmouthing the other parent or woman and it’s time for your friend to go and see a solicitor.

Speaking from experience a 13 year old is old enough to be told that their father has found a new partner and is moving out to live with them. I'm not suggesting that your friend bad mouths their father but at the same time it is important that the children are told the age appropriate truth and "we grew apart" is not the truth. My folks tried that and all it meant was that I was equally angry at both of them and was left with no "safe" parent to turn to. (They also got back together but that's another story...)

Factual info: their father has started another relationship. Don’t think lying helps matters.