I want to tell man's wife of affair, how do I build the evidence?

[Somersettler]

My best friend (F47) has been having an affair with a married man (M51) for 7 years. He has ruined her life while she has waited for him to leave his wife. My friend has neglected her family and friends in favour of him, and has never been interested in any other serious relationships with other men because of him. She's lonely, and turned to drink to ease her unhappiness. I think she's been unhappy for years because of him.

He has been stringing her along with excuses as to why now is not the right time to leave his wife, says he will eventually, says his relationship with his wife is dead. All the usual stuff. Every 6 months or so she would find the strength to try to end the relationship. Usually when he broke her heart letting her down, not being there for her, or generally treating her like the bit on the side that she has always been. But every time she's tried to get rid of him, he has come crawling back with gifts, and nights away and has always managed to keep her hooked on him. I hate him for what he's doing to her.

Tragically my friend has recently been diagnosed with terminal cancer. My grief and sadness has turned to anger at how he's made her so unhappy for so long. He won't be there for her when she needs him, he's not going to be holding her hand when she's going through treatment.

I want revenge. I won't do anything to upset my friend but if my friend doesn't make it, I absolutely intend to tell his wife. He's got away with it for far too long, and he's taking the piss out of his poor wife. He doesn't get to go back to normal when my friend passes away. I want to destroy him.

The problem is I don't have any proof of their affair. If I tell his wife, he can lie his, way out of it.

So I need to start gathering evidence. What proof do I need and how do I gather it?

As harsh as this sounds.... your friend only has herself to blame.
A woman knowingly engaging in a sexual relationship with a man knowing he is married/in a relationship already is no better than he is IMO. Both parties are to blame. You can't build happiness on someone else's misery.

It's awful your friend is now diagnosed with cancer, but that doesn't take away from the fact that she has brought her relationship situation on herself.

I agree that the wife deserved to know though.

She deserved to know 7 years ago.

Its too late now that the affair is over with.

Your friend sounds awful and needs to take responsibility for her actions.

She chose to have an affair - she could have told him she’s not sleeping with him until he left his wife.

She chose to wait 7 years.

She chose to neglect her friends and family over him.

She has chosen to be unhappy.

Stop treating her like she’s some vulnerable child.
She’s a grown woman who knows exactly what she’s doing and has chosen this life.

Why are you so involved with someone who is not actually a nice person and only thinks about themselves.

She would drop you in a heartbeat if he told her to.

And if you can't find evidence, tell her anyway. At minimum she will be warned.

This. All of this.

My Dear, I'm so sorry to hear about your pain in potentially losing your best friend in the whole world. I'm so pleased that you posted this story here. It will ease your burden. But I have something to tell you : You see - there is no such thing as ' RELATIONSHIP ' ...... RELATIONSHIP is a made up word by people, to project , on to others, what we think ' SHOULD " happen. You have been tricked ,also, by this WORD. To make things worse, zmen dont help, they just go around doing what they want ( married or not) rest assured, his Wife probably knows already and you will add to the drama by enlightening her. So my message today is: RELATIONSHIP is an illusion and people will do what they want, always, whether they're vommited to someone else or not. It goes on all the time. I BET HALF the people in your strèt have have illicit affairs. You need to live your Life KNOWING THIS ,as soon as you do. You will be wiser than you are today.

But the wife only deserves to know if your friend dies, if your friend survives, she doesn't deserve to know? She didn't deserve to know all these years? You don't care about the wife, do you?

I’m just going to try to answer your original question, without commenting on the morality or advisability of what you are proposing to do.

List of dates they've met / places they’ve been together?
Does your friend have any photos of the two of them together, that you could get?
Any details of the man's life that he’s told her and she’s told you?
Gifts she’s given him? Expensive gifts he’s given her? (Wife could check bank statement etc. to corroborate.)
Unlikely for you to be able to get this, but photos of text messages he’s sent her?

Honestly if that was my best mate I probably would have snitched years ago and gotten proof, but I know objectively that’s the wrong thing to do. If I was in your position I would also be very very angry and I would probably do something stupid (or I would be about to do something stupid and DH would stop me).

I know it’s hard and I know what it’s like to be angry, but you need to focus on being there for your friend first and foremost. Forget about this man. If it’s been 7 years surly the wife must have some kind of incling…

Its none of your business so other than supporting your friend you need to keep your nose out!

All you will achieve is dragging your friend’s reputation through the mud after she has died and disrespecting her wishes. Just leave it.

I'm sorry for your situation but your friend knew what she was doing and having a terminal illness doesn't suddenly turn her into the innocent party.
Just focus on supporting your friend not seeking revenge.

You were fine watching this affair for years, now you suddenly want to tell it all to the wife.

I would 100% tell the wife! Shameful that other women are telling you to keep quiet and let him get away with it.
But for now, enjoy the time with your friend and get your revenge later on. A letter addressed to her directly would probably do the job

Exactly.

If your friend wanted this woman to know she's been fucking her husband for seven years, she would've told her herself.

You have no right to blab the secret she trusted you with when she passes away.

There's no loyalty whatsoever in doing that, or do you think it's ok to be disloyal when she passes away?

Why would you set out to hurt his poor wife? She’s the victim in this, not your friend. If she doesn’t know you will be the one that destroys her family and she won’t thank you for it. You don’t seem bothered that your friends been sleeping with someone else’s husband and knew what she was doing and the consequences of that. Mind your own business and concentrate on supporting your friend.

Stay out of it is my advice. Yes he shouldn't have cheated on his wife but you friend is 50% to blame too. She neglected her friends and family. not him. Anyway you have no idea if his wife would actually leave him. Look on here at how many times the wide is told and is given evidence and chooses to stay.

Help your friend make peace with the fact that he is a weak man. He made promises to his wife to be faithful (he isn't), he's promised your friend that he'll leave his wife (he hasn't). He is too weak to keep those promises.
She needs her family and true friends around her, not some excuse of a man that uses her for sex.

Neither OP nor the friend cares about the wife.

They just want to use her as a way to get back at this man.

They’re hoping she’ll be so distraught that she’ll kick him out and he’ll either be alone or forced to get into a relationship with the friend.

The wife does not deserve to be used as a pawn in their childish games.

Honestly it isn't your place. Your friend here isn't blameless in any of this. She knows this man has a wife yet chooses to carry on with this affair with him, he's hurting her yes but he's also taking the piss out of his wife and so is she. Imagine you getting all this evidence then running to his wife once your friend passes. You go to her and say "sorry to tell you but your husband has been shagging my friend who is now deceased" she's going to think your friends a coward and coming to tell her all this once she's passed is just a cowardly move. You want him to pay for what he's done whilst your friend "gets away with it" because at that point she's dead and has no repercussions for her part in this man's affair.

Direct all your energy into supporting your friend. Why wreak havoc for the man’s wife? I know he has behaved like a total moron but his wife might have an inkling about his behaviour anyway.
By sticking your nose in you potentially put yourself in a vulnerable position when others support her and you look like to ‘bad guy’ for dealing out the gossip.
Leave well alone.

Your 'focus will shift' to 'revenge'? You sound as if your grief and anger for your friend are warping your personality. Please get counselling especially as you support your friend through terminal cancer.

You're right, his wife does deserve to know..thing is you're waiting until your friend is dead before you tell her..clearly you don't feel she deserves to know that badly otherwise you'd have told her a long time ago

You either tell the wife while your friend is here to answer any questions she may rightly want to know answers to from her side or leave well alone, it could tarnish your friends memory and make you look as though you supported the relationship for knowing but saying nothing beforehand.

Had your friend have wanted his wife to know she'd have told her herself, but she probably knew that if push came to shove she wouldn't have been the one the husband would have chosen.

She's a grown adult, knew he was married and could have walked away at any time yet she still decided that the gifts he bought her were worth more to her than her self worth.

Doesn't matter why she does the right thing, it's still 100% always the right thing to let the betrayed partner know about the probably diseased creature they are sharing a life with.

Everything from your OP aside, the wife deserves to know. The wife is the only innocent party in this and she deserves the right to choose what she does next with her life.