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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Original poster

Would you tell on a serial cheater?

43 replies

Wouldyoutellhim · 18/07/2025 20:52

If you knew someone was a serial cheater on their husband, would you tell them?

For context:

  • This person isn't using condoms when they cheat so is definitely putting their husband at risk of STI/STDs.
  • She's cheated with 3 men I personally know closely, she slept with each of them on multiple occasions/for a period of time (these I know for fact).
But I have been advised by a friend that she knows of others she has slept with. (I cant personally vouch for these)
  • Her husband adores her, would do anything for her and would be crushed if he knew. He has always wanted children, but she never did so he got a vasectomy to make her happy as its what she wanted, I find this sad that he has given up his chance of having children for a woman who cheats on him constantly. They are in their early 30s at present.

I'm not very close with her husband, we used to be friends but are just acquaintances now so not sure how I would even tell him. Just curious on opinions really

Part of me thinks I don't want to get involved and it's not my business, I also don't want the backlash for telling him etc. But I also would want to know if my partner was making a fool of me like that and I'd be humiliated if so many knew and kept me in the dark

YABU: It's not your business, stay out of it

YANBU: He deserves to know

OP posts:
DoYouReally · 18/07/2025 20:54

I would on the basis that if my partner was cheating on me and putting my sexual health at risk I would want to know and would also want to know I was being made a fool of.

ThreePointOneFourOneFiveNine · 18/07/2025 20:58

Managed to tap the wrong thing in the poll. You are definitely not being unreasonable. For goodness sake tell the poor man.

Anonusername1234 · 18/07/2025 20:59

I’d tell him! He may still have a chance for the life he deserves instead of this farce!

Tbf I’d have already told him not posted on MN about it! Just do it!

Bb14 · 18/07/2025 21:03

How do you know so much detail?

Original poster
Wouldyoutellhim · 18/07/2025 21:10

Bb14 · 18/07/2025 21:03

How do you know so much detail?

We used to be friends, we aren't anymore. We had a falling out a couple of years ago, which is why I am not friends with her husband anymore either.
I am friends with the 3 men I know she has slept with. They have told me themselves, they have no shame about it as from their perspective "they were single so did nothing wrong", so have been pretty open about it.

Because me and this girl had a falling out is why I haven't told her husband so far, as I don't know if I would be telling him for the right reasons, but I have no ill feelings towards him.

OP posts:
Original poster
Wouldyoutellhim · 18/07/2025 21:12

I have been aware that she has been cheating for a couple of years now, but it seems to be getting more and more frequent and he has recently gotten the vasectomy which is what makes me feel more and more sorry for him and how oblivious he is

OP posts:
Insomniapain · 18/07/2025 21:14

If you know so much about her extra marital sex life and at least one of your friends knows other details of her sex life she is obviously not being very discreet about her cheating.
How is it her H isn't aware ofat least some of what she's up to?
Actually it's surprising she is finding the time to have sex on so many occasions with so many different men.

Bagseverywhere · 18/07/2025 21:17

Yes. He surely must have some idea.

Givenupshopping · 18/07/2025 21:21

I think in view of your previous falling out, and the fact that her husband may already be aware, due to her lack of discretion, I would probably keep out of it OP.

I do think he has a right to know though, just don't think you should be the one to tell him. Maybe get the other friend who knows of more events to tell him?

Lmnop22 · 18/07/2025 21:25

I would tell him.

It’s always better to know and make an informed decision than to give up on being a dad and waste years of your life with someone who doesn’t respect you when you’d have walked away if you’d known.

Ultimately, he will decide what he can live with and will make a decision about his own future, but he ought to have the chance to do that with a full picture of what’s going on.

When my ex had an affair, I found out after that several people knew and didn’t want to say anything. It was very humiliating to know so many people had just let me think I was happy and respected when the opposite was true.

Original poster
Wouldyoutellhim · 18/07/2025 21:25

Insomniapain · 18/07/2025 21:14

If you know so much about her extra marital sex life and at least one of your friends knows other details of her sex life she is obviously not being very discreet about her cheating.
How is it her H isn't aware ofat least some of what she's up to?
Actually it's surprising she is finding the time to have sex on so many occasions with so many different men.

Edited

Most of them are her colleagues, we worked for the same company which is how we are all in the same circle and know each other. I no longer work at the company, I recently left which is one reason I am leaning towards telling him as if it does backfire on me for telling him at least me and her no longer work together. I think that's how she's been getting away with it, alot of people at work know what she does/has done, she's known as the office flirt but they wouldn't have any interaction with her husband really. Everyone knows what she's like so no one is surprised anymore, I think everyone's general attitude is they don't want to get involved and it's not their business.

Because we used to be friends is how I know the details about him wanting children and her not wanting any, they talked about him getting a vasectomy for a long time and he recently posted on FB really about getting the snip (I know, I know) 🙈 so that's how I know that's happened

OP posts:
rosesandkisses · 18/07/2025 21:25

I was in this situation OP - I chose NOT to tell him but distanced myself from both him and her, I have not spoken to either of them in years.

Their instagram protrays happy families.

If I had continued the friendship with them I would have told him. My logic for moving away from the relationships was that I could not in good consiousness continue with their dinner parties, and barbeques all whilst knowing its a huge charade.

Her husband was suspicious the last I heard and they started to fight sooooooo they had another baby! As that always makes things better!

Worse of it was she was cheating with another married guy who had just had a baby 🤢
it was all the texting and back and forth she was doing with this side piece that was the real killer for me, I mean a drunken snog on a works night out is bad enough but it went on for years.

If you can treat your husband that way, with protraying the perfect instagram family life - it shows me alot about integrity.

Whilst I am in no means perfect, I try my best and have chosen time and time again to be single and leave partners behind who were not right for me and head into the trenches of dating whilst living alone. Meanwhile, she got the comfort of a husband who adored her and was a family man. It really made my blood boil at the time. The whole house was filled with wedding pictures etc.

On reflection I am glad I did not tell him as I imagine it would have created a pile on for me as she had a loyal following of equally as nasty mean girls. I just did not need the drama.

I think he deserves to know, but you have to think about the fall out from it.

MsDogLady · 18/07/2025 21:26

@Wouldyoutellhim, I would absolutely tell him.

She has repeatedly and continues to make a mockery of him, steal his agency/consent, and risk his health. Surely all of us would want to be informed about this horrific truth.

Find a way to tell him. It’s the right thing to do.

rosesandkisses · 18/07/2025 21:28

Givenupshopping · 18/07/2025 21:21

I think in view of your previous falling out, and the fact that her husband may already be aware, due to her lack of discretion, I would probably keep out of it OP.

I do think he has a right to know though, just don't think you should be the one to tell him. Maybe get the other friend who knows of more events to tell him?

I would agree with this.

in my situation I had a couple of years of not being as close to the girl too.

EmeraldShamrock000 · 18/07/2025 21:29

I would tell him, a one off or intimate affair is differently to a list.

Berlinlover · 18/07/2025 21:34

I’d keep out of it, it’s just not worth the drama.

Original poster
Wouldyoutellhim · 18/07/2025 21:34

PP may be right, he might more aware than I realise. So many are aware of her behaviour and actions I would be surprised if he had no idea. He's always been really quiet and never really had many friends, spends a lot of his free time by himself playing games if he's not with her. This is how I think he has been kept in a bit of a bubble.

I think if I could find a way of telling him without it being me directly telling him (anonymously for example) I would definitely do it. I have always just tried to stay out it and not getting involved, but when I heard about the vasectomy it just really didn't sit right with me and it made me sad for him

OP posts:
pucksack · 18/07/2025 21:36

how do you know the husband doesn't know?

pucksack · 18/07/2025 21:38

Plenty of people turn the other cheek to infidelity & don't want to be forced into confronting it.

MissMoneyFairy · 18/07/2025 21:42

pucksack · 18/07/2025 21:38

Plenty of people turn the other cheek to infidelity & don't want to be forced into confronting it.

That's their choice though,if they don't know they don't have that choice. I'd tell him, if he knows then no big deal, if he doesn't know he can have the chance to decide what he wants to do.

BIossomtoes · 18/07/2025 21:42

pucksack · 18/07/2025 21:38

Plenty of people turn the other cheek to infidelity & don't want to be forced into confronting it.

This.

MissMoneyFairy · 18/07/2025 21:43

She has no right to put him at risk of a std

pucksack · 18/07/2025 21:47

That's their choice though,if they don't know they don't have that choice. I'd tell him, if he knows then no big deal, if he doesn't know he can have the chance to decide what he wants to do.

No, if he suspects & you tell him it could be a big deal because he is forced to confront it. it's also a choice to insert yourself in other people's relationships...

The wife is clearly not discreet, it's highly likely he has suspicions.

Original poster
Wouldyoutellhim · 18/07/2025 21:52

One thing I remember from our friendship is that he was always the sort of jealous and insecure type. I dont know if it's because he secretly knew but would never confront it directly or if he was obvious but would never be able to cope with the idea if he knew she did cheat. I always got the vibe he was scared of losing her

OP posts:
mylurcheristhebest · 18/07/2025 22:01

I wouldn’t say anything, if you were still friends with her would you still tell her husband? I don’t think you would, the only reason you are thinking of doing it is because you have fell out with her. As others have said he may already know