ADVICE PLEASE! Should I tell my kids they have a half brother?

[MalusPater]

Advice, please!
I have taken advice from several close confidantes, but welcome some independent input.

I am the parent to three, now adult offspring, from my previous marriage.
Whilst I was going out with their mother, as teenagers, long before they were all born, she and I split up for nearly a year (I instigated it, much to my later regret).
During that split, I became heavily involved with a married woman who was 5 years my senior.

I was 18, she was 23.

Our physical relationship came to an end when she became pregnant.

Our romantic relationship petered out soo--n ish after.

She was adamant that the baby wasn't mine, that it was her husband's.
I really doubted that because we often didn't use protection.
We relied on her using oral contraceptives but started using condoms later on in the relationship when she took a break from the pill.
My doubts were strong because not so long before she broke that news I distinctly remember a night at a party where things got a little frisky and she assured me that due to her cycle, she knew that it would be safe to continue without protection.
When she broke the news we agreed that it was for the best that she concentrate on rescuing her marriage and providing a loving family unit for her new baby.

Naturally, we kept things civilized and it all fizzled out.
To date, as he hasn't kicked my door down, wanting to take my scalp, I have to assume that her husband is thankfully blissfully unaware of the affair.

My girlfriend and I got back together, later married, and had 3 healthy children (boy/girl/boy).
We divorced nearly 20 years later, but I maintained a relationship with my children.

I later remarried, and in the spirit of honesty, I told my new wife of that affair decades before.

Fast forward nearly four decades from that affair, and one Christmas, several of us received as a gift, a DNA testing kit, so we could see where the family originated from, and to see if there were long-lost relatives.

I thought nothing of it as I posted my saliva sample.

Several weeks later the results arrived.
Nothing remarkable until I read the bombshell result that the child from my affair, decades before, was actually my son.
He too must have done a DNA test.
I immediately hid my profile and confirmed categorically with the DNA site staff that he was indeed my son.

I told my now wife and her son, plus his wife (as they had bought the test kit).
I also told my level-headed sister-in-law and husband, because I sought their counsel.

My decision was (and still is) not to make any contact with my eldest son.
Eldest, because he predates my son from my previous marriage. My son from my previous marriage refers to himself as the eldest son.

I decided not to make contact with my eldest son purely because he and his father (the man he loves and knows as his father) more than likely do not know the whole story.
For me to come forward would be akin to me throwing a fizzing bomb into their midst.
I have known these facts for a couple of years, and whilst curious about him, have to think about him and his father.
In their case, ignorance may truly be bliss.
My confidantes agree with my decision and rationale for staying silent.

Unless he comes knocking on my door for answers, then it's a secret I have to keep from him.
I have no idea where his mother is (but I know she has since divorced), but I would most definitely tell her the result of the DNA test. She should know the truth. I can't carry the knowledge of this alone.
It even ran through my mind that should he become ill, she should know because I could be a suitable donor for some conditions.

My real dilemma lies with my three children from my previous marriage.
I have always been upfront and honest with my kids.
As much as I need to tell them the truth, I feel that to do so could be damaging.
Admittedly, their older half-brother was conceived whilst their mother and I had split up, but I know that they would be angered because I didn't spill the beans as soon as I found out.
If I did tell them, it's, without a doubt, they would want to know who he is.
To tell them would then throw that fizzing bomb into his, until now, totally ignorant of the facts, family unit.
It's not fair on him and them if I do.

Your views on my dilemma, please.

OP I found myself in a similar position to your oldest son, although I was given up for adoption. Decades later through DNA I discovered I had 3 half brothers. One is only 11 months younger than me. Initially I reached out to a nephew and it did take everyone a long time to digest the info. It is difficult to judge how people will react. In my case I think they were cautious of my intentions.
Nobody was aware of my existence. My Bio mother (I found her age29) had never been upfront about who my father was. He was from an ethnic minority, so when that appeared in my DNA results it made me question things.
To cut a long story short I discovered my biological father 5 months too late. He had passed away, but eventually my brothers agreed to meet with me and we are all on good terms. Nobody is blaming anyone for something that happened decades earlier.
In your position I would send a brief and thoughtful message to your 1st son via the website, reaching out to him and give him time to digest and respond. You don’t have to tell everyone all in one go.
Don’t be too harsh on yourself for decisions you made as an 18 year old.

Yes, of course you should tell your children.

If you were my Dad, I wouldn’t be too upset about a baby that was conceived when you were not with my Mum, and you were told was not yours, and had had no contact with.

But I would feel furious and betrayed that you had told your subsequent wife, and her son, and not me.

And stop all this patriarchal ‘eldest son’ stuff. It is just as important to your daughter and younger son. Why should you or your son assume special status to ‘eldest son’?

Tell your kids.

You risk A LOT if some Christmas Present gift to your first child results in them getting notified that way.

These things happen. You were 18, the woman told you it was her husbands child and chose to bring the baby up in her marriage. She had that right.

I would not go throwing bombs into her family. But be honest with your own.

Be honest with your 3 children. You should've told them before your step son. I doubt they'll 'hate' you when you were only a teen and wasn't with the mother of your 3 children at the time. You didn't do anything wrong. That older woman was in the wrong for taking advantage of a teenager and then lying to him that the child was her husband's. I wouldn't reach out to the other son though.

‘I wouldn’t reach out to the other son though’.
why not?
I was this ‘other son’.
I feel that everyone should know who their parents are. If for no other reason for health info.

If you had told no one when you received the results you could have kept quiet about this.

However you have told various family and friends. I therefore feel you have a duty to tell ALL your children what you have found.

What about your Will?

Will you leave your estate to your ‘children’ or name the 3 from your marriage and leave #1 to inherit from their parents (the people who brought them up).