Need advice on complicated family dynamic

I would say all three of you- you, your DD and the DS are still grieving, which is not the right time to make a big decision. . A massive bombshell like this could be incredibly damaging for everyone concerned, and might not be the clean break you hope for. Your DD is at a tricky age anyway, to find out that you and DH kept this from her for all this time could be very difficult for her.

I would just put the decision about telling him to one side for now. You’re absolutely within your rights to keep him at arms length, make excuses about Christmas, be polite but keep your distance. Give it at least a few months for things to settle and then see how you feel.

I thought,the dad knew from age 5 ,he wasn't his son

Well yes-but no one thought to tell the son!

I mean he still could be!

How do you or your DH know that he wasn’t DH biological child? If it was only based on the ‘admission’ of a person who may not have been feeling very benign at the time, I would keep a very open mind about DSS parentage.

Of course , it doesn’t make any legal difference to your decision, he has no ‘right’ to contact with his putative half sister. Anyway, it’s a definite no to Christmas, that’s an invitation which needed to be earned.
Edit:
Sorry, hadn’t read the full thread, so probably redundant…..

Where does it say he may be the son ,
I've obviously missed that bit .
I thought,the dad knew from age 5 ,he wasn't his son
Apologies if I've misunderstood

He's your dds half brother, that's how they've been brought up. I think yabu not to facilitate contact over Christmas.

But OP doesn’t want to tell him the truth out of any sense of justice or feeling he needs to know. She wants to tell him because she is bitter and hates him and wants to get rid of him. Her motivations are pure spite and nothing more.

Also, it’s entirely possible that the bloke is actually his father’s child. There’s no way of knowing. And if I was him I’d be demanding a DNA test with the sister to prove it, purely because of how it looks - as if the stepmother is sticking the boot in to get rid of him as soon as his father’s died.

Not kept in the dark

I think everyone is forgetting
The op and DD have just lost their dad and husband.
This is a man of 30 ,not a 13 year old boy .
He needs to be told the truth ,and kept in the dark with this ridiculous lie

Please don’t tell him about the possible parent issue by email - if he is low and alone, sitting with questions that no-one can answer.

Perhaps done face to face over a lunch in the New Year?

Yes to saying that you aren’t up to doing Christam given the circumstances, and shutting it down that “you are going away”.

So he thinks that he has recently lost his dad, having previously lost his mum?

Bloody hell!

This is what I came to say buy both “kids” and ancestry dna kit for Christmas “won’t this by fun to find out about our heritage!!!”then act surprised!!!

As for Christmas don’t have around but can you go out for a Christmas Eve breakfast something quick but still catching up, the DS might be awful but he still thinks your DD is his sister and that’s not your, his or her fault your DH and DS’s mum shouldn’t have taken their secret to the grave

I’m going to go against the grain.

I understand that you don’t like the DS and you don’t actually want anything to do with him, but to tell someone almost as soon as the parent they knew as a parent has died that he was never their father and the sister he knows isn’t his sibling is a bloody shitty thing to do - it really is. You shouldn’t feel obliged to see him at Christmas, but to destroy his life like this really doesn’t show you in a good light. At all.

I feel so incredibly sad for DS. Lied to in the most destabilising way and now no parents or anyone really.

I do completely understand your feelings also. If he was a joy to be around I'm guessing you'd feel differently.

I think the level of rejection he'd feel if you are cruel in your delivery could be catastrophic for this guy. I think it's kinder to just be unavailable and communicate that in the kindest way possible.

From the limited information you have told us
It's hard to give proper advice, without knowing exactly how much time the son spent with his dad ,and with you and your daughter
My instincts say ,to keep him away from your DD
Don't be letting some random man have access to her
Although ,I suspect he will want a DNA test , especially as he is keen to see dd

Ok, so I can pretty much understand how you feel.

What's dds version? Given this to all intents n purposes is her brother. I doubt neither child would be particularly thrilled at this revelation. They've both just lost their dad. Losing a brother/sister too might be harsh. Sure....he's NOT your responsibility. Horrible' thought but ...if you go he's all she's got.

The only person you owe anything to is your daughter. And I would tell her the whole story. You may find that once she learns he isn’t actually her brother, she doesn’t want to see him.
And why would you consider hosting him at Christmas when you know he doesn’t like you? I would just say no that won’t be possible, and wait to see how your daughter reacts.
And remember this isn’t your fault.

Oh god that's awful
I don't want to speak badly of your husband, because he's died ,but ...
What was your husband thinking, leaving you in this situation.
He should of told him the truth before he died ...unless his death was suddenly,then he couldn't.
But even so,that lie should not of been left at your door .
This should not be your problem
Absolutely tell him the truth ,he's a grown man .
What about inheritance
If your husband is on his birth certificate,and you die ,do you want him trying to claim half of your daughters money...have you done a will
How close were the son and dad ..that would effect any decisions,if they saw each other every week and had a close relationship,that makes it tricky too
A

Also, I think you need to be fair to this man whether you like him or not. Be clear in your mind that he isn’t at fault for any of this. This is all your DH’s doing, for keeping this unconscionable secret. He may have done so for the sake of the then-boy this man was. But he had 30 years to rectify the situation and didn’t, took it to his grave and left others to deal with it (same goes for his mum btw).

It’s shockingly cruel when people do this to children who grow into adults. It’s absolutely destabilising and sometimes destructive. This 30yo man has done nothing wrong. You, not remotely related, know more about him than he does. Whatever your feelings towards him, don’t let cold-heartedness be one of them.

If you tell him he wasn't his son, then if he's not he'll probably blame you, but if he does turn out to be his son then you've given him a stick to beat at you with.

Yes, this is a good point. I think I'd frame it as 'Your Mother told DH when you were a baby that he was not your father, but he already felt committed to you and wanted to be in your life, even if that was true'. That covers you if she was lying and just trying to get rid of your DH from her life.

I think this is a good idea.

If nothing else your dh and the ex's relationship sounds pretty dysfunctional and it's always possible the ex told him that, but that wasn't true.

If you tell him he wasn't his son, then if he's not he'll probably blame you, but if he does turn out to be his son then you've given him a stick to beat at you with.

Surely he has the right to search and possibly find a df and siblings? Maybe he knows and his attitude is a reflection of living with lies all around him.

Whatever your motive OP and whatever you personally think about him, I think he deserves to know who he is and it would appear that you are the only person still living who can give him that information. Currently, he believes himself to be an orphan, but his real father, whoever he is, may still be alive. It would be a really decent thing for you to do if you could share that information with him so he can do as he wishes with it. As a PP suggested, I would draft an email to him and as kindly and sensitively as you can, give him the information. As for Christmas - just say no. You owe him nothing more than the above. My condolences on the death of your DH

If your husband did nothing about the paternity situation I would consider him to be your stepson and not get involved with the paternity issue.

There's no detail about how this man is awful so it's hard to comment on that, but I think it's reasonable for him to have a relationship with his sister, unless you have good reason not to allow for that of course.

You don't have to have him over for Christmas day I suppose - maybe another day over Christmas? Has he somewhere else to go? I think a relationship with your daughter is reasonable in the long term.