Such a horrible situation

[iguanabanana]

Background : my husband 's ex w had affair resulting in end of their marriage. She is now married to affair man (AM ).
They had 2 children, both now teenagers.
A few years ago AM' s estranged wife got in touch with my husband out of the blue - don't know how she got his details. She has since messaged several times over past few years.
She is convinced that AM is natural father of my husband and his ex wife's youngest child.
She wants to confront them and get dna test etc.
The thing is, long before she got in touch, my husband confided in me that he suspected that youngest child wasn't his (ex's infidelity, the different way she treats that child, eye colour...).

I have suggested that no good can come from this, it could only lead to heart ache. But if this the right advice? Opinions welcome.

I am generally a fan of people knowing about their origins where possible, even if that knowledge is complicated. But this wouldn't be about that; this would be some weird point-scoring exercise by Affair Man's ex which doesn't remotely place your stepchild and their life and needs at the centre of the situation.

Your husband has opted not to do anything about his suspicions previously, and has presumably thought that through. His reasoning shouldn't be altered by the presence of some random harpy out for vengeance, a woman who's prepared to use a teenager as a tool to achieve that. That should certainly be a hard no for your husband. He already suspects he may not be this child's biological father; someone else also suspecting that changes nothing at all. Your husband is this child's father, whether or not that's biologically the case, and the child is the person who matters, here.

With that in mind, I'd personally be concerned that the former Mrs Affair Man might be disruptive towards that child, in her quest to do whatever the hell it is she's trying to do. If there's the slightest possibility that she might contact them, by whatever means, then your husband needs to stand ready to support that child. It might also be prudent to loop in his ex - not in an accusatory way - depending on the dynamic there.

Why is AM’s ex so bothered about this? What actual difference would it make to her life if this is true? Why is she stirring g the pot after all these years?

Your husband has to decide what he wants to do, for him and him alone. A random person popping up and going over the situation is irrelevant. Your husband either wants to find out (and there is a case for finding out, genetically) or not (and there is a case for not finding out, on a personal level)

Don’t be swayed by someone who has no link to the situation in any material way suddenly wanting to ramp up the drama.

It’s up to your husband. Why hasn’t he got a dna test before if he’s suspicious? How does his ex treat that child differently?

Wait. She thinks that AM is your DH's Father?

So is potentially saying that DH's Son could actually be his brother?!

That is a very odd thing to be spouting and could be troubling for a teen to hear via the grapevine. I'd be requesting a test myself to shut her up!

@PinGwyn No, she's saying her exH fathered a child with the woman he was having an affair with. The woman is OP's ExH.

@PinGwyn

No she isn't saying anything of the sort.
Try reading it again.

Haha. OP's H's ex.

Yes, it's complicated!

Oh god, I read that completely wrong!!

Thank you for replies, to answer some of your questions, my husband has niggly doubts since finding out about the long standing affair, but has nothing solid to go on.
His relationship with both children is very good.
He thought about dna test, but like other posters have said, he is the child's dad, and finding out that dna shows different can only lead to trauma. The child is central to this, we can't bear to think what it would do to child to have this questioned.
Good point about om's ex - there are ways she could possibly contact child. We will have to remain vigilant.
As regards letting child's mum know, this is a tricky one, she can be quite unbalanced and defensive... I will talk to husband about whether this is doable. Thanks.

we can't bear to think what it would do to child to have this questioned

I mean, it's not necessarily the worst thing in the world to recognise that the question exists in at least some people's minds - because it's actually perfectly possible that the child themselves has asked themselves this question, or will at some point, especially if they're at all aware of the circumstances surrounding their parents' split. The key thing, I think, is that if it comes up at all it should be in a way that surrounds the child with love, and recognises the reality of their bonds with all the adults in their life, genetic or otherwise. Not just having it chucked into their life because some rando has a strop on.

I wonder if it would be helpful for your husband to explore this with a counsellor with experience in dealing with these kinds of family dynamics? It might be helpful if he had a chance to explore how he could best respond supportively, should the question every arise.