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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

How to deal with this situation? BIL & his kids as a result of an affair?

299 replies

jojobooh · 20/11/2025 14:41

Basically my BIL had an affair behind his long term partners back (has a son (10) & a daughter (14) with her) which resulted in twins being born who are now 5.

The kids have never met and are not aware of the existence of each other because of several reasons.

We have DC who are closer in age with the twins and have play dates often.
Our oldest DC talks and understands and is very cleaver.

DC see both lots of cousins, obviously separately and are aware that they are cousins and family etc.

Were having a Christmas party for all the kids in the family next month in our home, just abit of festive fun for the kids.

Now as the kids are not allowed to meet each other BIL wants us to host the party twice to neither of the kids miss out.
I think this is absurd.

Whilst we want all the kids to be treated fairly and equally I find this request unfair and OH is supporting BIL.

Why should we have two parties?

Moving forward I think this will be a similar trend when DC have birthday parties etc or other future family events we host.

And when DC are older they will be forced to keep this secret which I don't think is fair or right at all to swear young kids to secrecy.

I just wanted to see if I was BU about refusing to host this second party and if anyone else has been in a similar situation.

OP posts:
TheHouseElf · 20/11/2025 18:35

Your BIL sounds like a douchebag, and your DH doesn't sound that much better OP, defending his behaviour and doing this aggressively towards you. I'd be questioning my future with him, and the rest of this family quite frankly.

FancyBiscuitsLevel · 20/11/2025 18:36

Oh love you need to leave and let this be your exHs problem.

But if you aren’t at that stage yet, just message BIL yourself and say you won’t tell your children to lie, you won’t host two events. As far as you are concerned if your children tell their older cousins about the younger siblings he is hiding from them that is his problem to fix.

RightSheSaid · 20/11/2025 18:42

So your husband is his ally and his alibi. Your H is complicit in the deception. BIL is a shit dad and partner but unfortunately so is your husband. They are like two peas in a pod. And, on top of that your H is a nasty, evil, abusive, bully. Why don't you step away, run, from this family and protect your kids from these shit men amd this shit show? I know its not easy. You are worried about doing the right thing by BIL kids. I think you need to do the right thing by your own kids.

Iwillcomeouttheotherend · 20/11/2025 18:52

Please, please forgive me …. I know this is a very serious and messy issue …. However, this comment has given me the belly laughs 😂😂😂 and I can’t stop 😂

“The 10 and 14 year old witnessed domestic abuse” …..
BIL doesn’t come out of this sounding like he should be up for the Father / Husband / Partner of the Year Award.
…. and could the domestic abuse have contributed to the ex wife turning to the bottle! Oh sorry I forgot - it was HER DRINKING that MADE HIM have an affair😳

No way should you be organising 2 parties.

The longer this goes on …. The bigger the fallout for those poor kids when they eventually find out. And find out, they definitely will.
That will be a massive head f@ck for all the kids.
What a mess your BIL has created.
I ABSOLUTELY cannot fathom out why your husband would be supportive of the BIL.

Good luck with your Christmas party.

Autumngirl5 · 20/11/2025 18:52

This is complete madness! I can’t even think what it would be like to be involved with these family issues and dynamics.

diddl · 20/11/2025 18:55

He has he own place so can organise two parties or one for the kids that don't make the cut to yours.

On another note, what a family you have been unfortunate to marry into.

Ophy83 · 20/11/2025 19:00

Just stop lying for this awful man!

Arlanymor · 20/11/2025 19:04

jojobooh · 20/11/2025 18:28

OH gets nasty in terms that he talks to me in quite a belittling way, patronises me and raises his voice.

He can actually be quite verbally abusive to me and has a really evil/bullying side to him.

Our relationship is far from ideal/perfect but that is a whole different thread.

I will be talking to him tonight when DC go to bed.

Good luck - you are doing the right thing.

Sounds like once this issue has been dealt with you might need to come back and start that different thread, because it sounds like a horrible way to live.

But as I say, you are doing the right thing - putting the children first. Good for you for breaking this cycle of madness.

WearyAuldWumman · 20/11/2025 19:07

Autumngirl5 · 20/11/2025 18:52

This is complete madness! I can’t even think what it would be like to be involved with these family issues and dynamics.

I taught in Scottish secondaries for 40 yrs. In that time, I can think of a few similar situations

One father had one set of children living in one town and another set living in a town only 15 miles away. The children found out when they were teenagers.

Another case - Dad was a lorry driver. Yup. He had one family in Scotland and another in England. Again, the children were at secondary school when they found out.

The father moved his English family up to Scotland and enrolled them in the same school.

The third case that I can recall: again, the kids found out at secondary school...when it became apparent that a neighbour's teenage son was the spitting image of the father.

The children were - understandably - furious. These men are always caught out eventually. The best that the OP can do is to ensure that she's not embroiled in the cover-up.

Mrsknowitall · 20/11/2025 19:07

What happens if there is a family wedding or christening? Do you all have to do it twice! That’s madness and so unfair to all the kids

WiltedLettuce · 20/11/2025 19:11

I would just uninvite the lot of them. Far too complicated.

Millytante · 20/11/2025 19:15

jojobooh · 20/11/2025 18:28

OH gets nasty in terms that he talks to me in quite a belittling way, patronises me and raises his voice.

He can actually be quite verbally abusive to me and has a really evil/bullying side to him.

Our relationship is far from ideal/perfect but that is a whole different thread.

I will be talking to him tonight when DC go to bed.

I think he and his brother are the type of man the Wise Woman had in mind when she wrote that we really have no idea just how much men hate us.

Naturally we all recognise the very worst manifestations of such misogyny, in terms of the extreme violence and abuse that never cease. We’re aware there, because of the depth of our outrage.
But in normal, humdrum lives such as most of us lead, we often take a much more commonly experienced type of male hostility as our lot, because a widespread culture still persists where it’s accepted that ‘this is just men’s way, and after all, he's a good dad’ and all that baloney.

(By the way, training a young child to lie in order to let one’s uncle avoid detection as a marriage cheat, is a damn good way to perpetuate this culture.)

It’s so bloody tiresome watching men like this BIL have rose petals strewn in his path, though he leaves a trail of abandoned, misused women and children behind him.
Look at OH excusing the BIL still having it off with this other woman, though apparently she’s ghastly.
This never matters with men like that, as long as there are tits and arse on offer. Her conversation and personality do not register on his mind at all, because women just do not matter, they are not as worthwhile as men, and that’s the truth of their world. They are merely receptacles for lust (and the more she erases herself and becomes a cartoon, the better)

I think it’s high time all these men were forced to adapt or die off, myself. They should have mended their ways years ago voluntarily, as general education penetrated their skulls, but now the situation calls for enforcement.
Not for us to coach them (to hell with that) but simply to avoid private dealing with them, and in particular, no longer shagging any of them.
Once they haul themselves out of self-satisfaction and male entitlement, maybe we’ll talk. Say, around 2060.

Dollymylove · 20/11/2025 19:16

jojobooh · 20/11/2025 14:53

I don't agree with any of this.
It is very unfair on the children involved.

By saying DC are clever - I meant that eldest DC is aware they they are all his cousins and in the future could accidentally let the secret slip in future.

Everyone in the family knows about the twins it's just BIL's middle children (10 and 14 year old) who aren't aware.

We treat them all the same and OH makes a big effort with both sets of kids.

His middle children? Christ on a bike how many has he got?
Is he still with any of the mothers? Do they know about the other children?
What a mess!!
His children should all know about each other, imagine the shock if they find out years later !!

BuckChuckets · 20/11/2025 19:18

BIL sounds like absolute scum, and your OH doesn't sound great for taking his side all the time 🫤

Kiwi09 · 20/11/2025 19:19

@jojobooh can you push for BIL to tell the kids now and then they could get use to the idea before meeting at the party? Definitely do not have two parties!

The longer this goes on the more likely it is that all the kids will hate him for keeping this a secret….and potentially want little/nothing to do with him in the future.

TrippingOverMyAssets · 20/11/2025 19:23

jojobooh · 20/11/2025 16:19

The oldest two kids are early 20s (BIL was 17 when he became a dad).
They didn't see their dad for years and the kids lived with their mum and grandparents.

BIL came back into their lives when they were 12 and 13.
They have serious daddy issues.

They have been involved in stabbings, drugs and one is currently incarcerated for a stabbing.
BIL used to go clubbing with them and allow them
to smoke marijuana.

The 10 and 14 year old's have witnessed domestic abuse, their mom is an alcoholic which is apparently one of the reasons why BIL had an affair apparently.

It is very unfair on the kids.

I have tried to approach this with OH but he gets nasty and very defensive of his brother.

Jesus Christ! He shouldn’t be in ANY of the kids lives.

WeNeedToTalkAboutIT · 20/11/2025 19:25

Y'know, if you get rid of your vile OH you won't have to deal with BIL's insanity...

Hotchocolateandsnowing · 20/11/2025 19:29

Could you compromise and have the party 12-5. The first 2 hours with one set and the last 2 hours with the other set. So it’s not any extra planning / food but they all get to come?

I know it sucks but it’s that or none of them can come to make it fair.

user836367392 · 20/11/2025 19:35

Thundertoast · 20/11/2025 14:46

What does your BIL say when people ask him what the plan is for both sets of kids finding out?
Have you discussed with him the fact that your kids are old enough to let it slip by accident now?

Is it just his older kids that don't know? Or does his wife know?

Uricon2 · 20/11/2025 19:38

jojobooh · 20/11/2025 15:14

I only became aware of this when I had my oldest DC as it was only the parents and siblings who knew at this point.

I only found out when OH told me as the twins mum had wanted to meet my baby.

None of the two sets of children know of other's existence.
BIL also has two older kids who are in their 20s who know.

The twins mom is abit weird , she obtained BIL's then partner and now ex's number from his iPad and called her up and asked "So when are the kids meeting then?"
This was how she found out about them.
The twins mom then began stalking her.

From what I understand BIL dosent want the 10 and 14 year old to know because he is scared the kids will hate him.

They're going to hate him a lot more when they realise the extent they've been lied to.

I would have nothing to do with this. It's utter madness.

user836367392 · 20/11/2025 19:41

jojobooh · 20/11/2025 15:14

I only became aware of this when I had my oldest DC as it was only the parents and siblings who knew at this point.

I only found out when OH told me as the twins mum had wanted to meet my baby.

None of the two sets of children know of other's existence.
BIL also has two older kids who are in their 20s who know.

The twins mom is abit weird , she obtained BIL's then partner and now ex's number from his iPad and called her up and asked "So when are the kids meeting then?"
This was how she found out about them.
The twins mom then began stalking her.

From what I understand BIL dosent want the 10 and 14 year old to know because he is scared the kids will hate him.

Each one of his 6 children will hate him if he doesn't tell them

MissDoubleU · 20/11/2025 19:44

This whole situation is a mess, beginning actually with your own DH. Leave him and his sleaze brother to their messes and get yourself free. None of this is normal girl.

jojobooh · 20/11/2025 19:49

OH has just called BIL's ex a "crazy woman" and when I have advised him what a weird and messed up situation is he again has turned nasty and started an argument.

He thinks there is nothing wrong with what has happened and thinks the kids will play happy families when they turn 16 and apparently it's BIL's ex's fault they have not met as she is "crazy".

Now he is trying to say BIL told the ex he wasn't happy for years and the relationship was over.
Thats a lie as they lived together in her house.

She threw BIL out when she found out and he came to our house with a bin bag of cut up clothes saying that she had attacked him because he tried to stop her from steering the wheel when he was driving with her and the kids, she had keyed all his car up and there was me feeling sorry him.

OH response to my question when I asked him how he would explain this to our kids was "I will simply say his uncle loves women and sex".

He is truly awful and I know he is bad as his equally awful brother, it's the kids that tie us nothing else.

OP posts:
seasid · 20/11/2025 19:53

I think you’re being unreasonable in the first place for you and your children being aware whilst his kids have not the slightest idea. I think it’s disgusting that this is going on behind their back - yet you seem to be fine with keeping that secret from them, telling your children to keep that secret, but the party is where you draw the line??? Because it now affects you huh?

Shortandfatandpaleandlovely · 20/11/2025 19:54

Your relationship is definately far from ideal, it's abusive, and your children are seeing it, and learning that it's acceptable to be in a relationship based on bullying and belittling.

I wondered how any man could support his brother behaving in such a crazy way, when you explained how your partner treated you it made sense - he doesn't respect women at all, including you, and isn't bothered about the impact of poor parenting, as doesn't care about the well-being of the kids in his family, including yours.

You and your kids only have one life.

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