AIBU to think telling your partner something I told you in confidence makes you a bad friend?

I largely agree with the OP but it depends on context.
I have a friend who I used to share everything with until I learned that she tells it all to her partner. Problem is, he is a weed smoking over thinking paranoid kind of guy and thinks he is super intelligent and great at analysing people (he isn’t) so they usually sit and pull apart everything any friend has told her and he delivers his ‘verdict’ and she believes it.
I don’t tell her anything personal anymore as it’s caused me big issues in the past. I’m considering cutting her off completely to be honest.

Does she not feel even a tiny bit of shame about it?

Because you care about your friend? Because he wants to discuss how best to approach the situation?

I have a friend like that, she is a gossip and can't keep anything to herself. I found that out the hard way.

I now joke with her that I wouldn't tell her anything about my private life that I wouldn't put in the local newspaper.

Some people just HAVE to tell other people stuff they are told. I have a friend like this. She’s currently single so she tells me loads of stuff she should not. I don’t want to hear it ever.

I don’t share anything with her now a so don’t know who she might tell.

not really sure why she’s still
my friend 🤣

You're implying that expecting confidence from a friend is some naive little oversight on the other person's part, rather than actually being the wrong move on the friend's side to havbe no reguard or respect for a friends privicy . Just because loads of married people apparently do this doesn't make it fine, or make them good, respectful friends, it just means it's common, those aren't the same thing.
And the "spinning out" bit reads a bit smug to be honest, like you're almost pleased at the idea of people realising they can't trust who they thought they could. Of course people are unsettled by that, finding out something you assumed was safe and just between you and a friend might actually have been passed along the whole time is a very valid thing to 'spin out' about

I tell my husband everything and my friends and family know this.

Although he wouldn’t tell anyone else or even mention it unless the person spoke to him about it.

This is my take on it - I always assume that anything I tell a friend will be shared with their partner unless I specifically ask them not to. Of course that doesn’t make them a bad friend!

Interesting how this has pretty evenly divided Mumsnet though. I wonder how many who voted YANBU ’ are now spinning out, wondering which camp their friends fall into!

Sharing their private confidences with others is not a moral imperative however you want to dress it up as such.

Precisely. Other people’s marriages are their business, not mine.

And yet, whilstever my husband wasn’t cheating on me, what a member of another couple chose to do as absolutely nothing to do with me, friends or not. If my husband was told in confidence that one of our friends was having an affair, why would he tell me?

I don’t think you are that close with your friends if that’s how you’d feel about the man cheating on the woman in a couple you’re friends with?

You just need to tell him your friend needs support. That should be enough. It would be for mine.

Sometimes you would need to tell your husband especially if it is going to impact your relationship such as having to spend more timecwith friend. I would ask friend first though.

I find that completely odd.

Sharing a friend's secret she has confided in you, with anyone, including your husband is wrong.
Asking if you can is not only wrong....it's bloody weird.

This is such a great post.

It really is shocking that around 50% of people who have responded to this thread value gossiping above being a true friend.

What difference would telling you have made? It’s none of your business.

My DH wouldn't want to know. Even if I did tell him, it would go in one ear and out of the other!

Eh? No? Where did you get that? I meant I’d be upset that my husband had effectively gone along with the lie the male friend is telling his wife and not told me about it. I think that was rather obvious.

That's very differnt thoug. In OP's case, her secret doesn't involve her friend's husband at all, it's not information that's actively harming him or deceiving him by omission. Your example only really works as a "would that hurt you" scenario because the secret is directly about someone lying to your husband's face for a year, that's not comparable to a friend sharing something personal that has nothing to do with either husband.
A better comparison would be something like, would you be hurt if you found out your husband's friend told him he was abused as a kid, and your husband sat on that for a year without telling you? Or could very well something less 'heavy' but still personal lik had a threesome oand so on along the same lines. That's the actual equivalent, someone's own personal information, not something that's actively deceiving you or someone you love.
Your example isn't really a parallel, it's a bit of a whataboutism, it swaps in a totally different kind of secret (active deception affecting your own marriage) to argue against a totally different kind (someone's personal disclosure that affects no one but them).

That’s interesting, I think a lot of people would feel differently about their friend being cheated on by her husband.

Is the implication that if you don’t share your friend’s personal issues with your husband/boyfriend you will do the same or you are responsible for it?

So if I don’t share Mary’s private marital/health/financial worries with my husband then I’ll suffer or deserve the same?

Confiding a private problem in a friend is just that. I’m not confiding in her husband.

I wouldn’t ‘feel’ anything. Not my relationship to worry about.

Say you’re friends with a couple and the man in the couple tells your husband that he’s having an affair but says “don’t tell anyone”. Then when it all comes out your husband says “yeah I’ve known a year”. How would you feel?

I personally don't divulge things to one member of a serious relationship, if i'm not comfortable with both of them knowing.
I don't like the idea of making someone keep a secret from their serious partner. Ok if it is something silly like I've done something embarrassing then its not "bad" if they kept it from their partner, and i might be a bit embarrassed if they knew,but if it is something "heavy" that can make them feel bad/upset etc i'd never want them to not have their partners full support.
I always specifically say if it is something i'd like them to not share outside of the couple though, and i've always asked if it is okay if i shared with my partner (back when i had one) before sharing.