OK, have changed name for this and a few details just to be on the safe side.
Last night my DH told me he found out that his dad is having an affair. He said he found out 'ages ago', can't remember exactly when but guesses around a year, bit less maybe.
Apparently dh was suspicious because his dad was always fiddling with his phone, hiding it away etc (can't say I noticed this really) and he looked at his dads messages. He can't remember exactly what they said but he is sure that they couldn't be taken any other way. The OW is a friend of his dads, they have been friends for over 5 years, his mum knows her and she goes to the house as a 'friend' to see FIL and he meets her socially in a group (or so MIL and everyone else is lead to believe I suppose). MIL has told me about her, just calling her a friend of his, I never really thought anything about it tbh and I guess she hasn't either
Anyway after finding these messages, he has checked up a couple more times, latest being over the weekend when we were visiting. There are still messages there so its obviously still going on, not sure what prompted DH to tell me this time, but I guess he is getting sick of keeping it to himself. FIL doesn't know DH knows.
Now I know it kind of makes sense, I am not particularly shocked. It explains FILs behaviour sometimes and a few weird 'incidents' that have happened. One example is when MIL gave me a pair of knickers she had found down the back of their bed (we use their room when we stay so we have space for the DC's in with us). I told her they weren't mine, maybe they were dh's dsis'. She says deff not (SIL is still living at home) and we gave each other looks. MIl then said they must have been from when SIL had a party and a load of friends were over, as she was suspicious some of 'that kind of thing' had happened. I never thought anymore of it, but when DH told me it now makes sense
Basically DH and I now don't know what to do. DH says every time he speaks to FIL he feels angry, he really hates him for this and what he is doing, but is nervous of doing anything. I can understand because I guess he holds the key to breaking up his family. I have told him its not him who has caused this but FIL being a arsehole, but its still on his shoulders whether or not it gets out and he is torn. Would they all be happier just not knowing? I am not so sure, MIL isn't exactly happy with their relationship I know.
I just feel so sorry for MIL, he often treats her badly, little respect etc etc, I wouldn't stand for it personally but I always keep schtum about my opinion as its not really my place to say anything. Now I know this though I just want her to leave him, I hate that she washes his pants and cooks his tea every day while he swans about with the OW she just thinks is a friend. They have been together since Uni way back when though, and tbh I even if she knows I have a feeling she wouldn't leave him. Then there will be loads of tension where she knows we know that she knows etc etc. Its so complicated and sad for everyone
There is always the possibility that she already knows I guess, if even DH was suspicious surely she would be too? But the OW comes into the house and acts like a friend and MIL talks and jokes with her, no tension (from MIL anyway). I met her in PIL house and thought she seemed edgey, I just figured that was her, now obviously makes sense. MIL was her normal self though and I guess she wouldn't be if she knew.
So I don't know what to advise DH to do and thought I would get the MN opinion. Does he confront FIL? FIL will undoubtedly deny and poss they destroy evidence before MIL finds out. Go straight to MIL and tell her to check phone herself? Or not say anything and keep it to ourselves forever? DH is going mad with this info eating him up for ages now, I have a feeling him telling me makes it all 'real' for him and he might be ready to let it out in the open.
DH is terrified of destroying his family and 'ruining everything' we all have. Any words of wisdom for him? If this were my family I think I would tell my mum, but she is very different to MIL and so is the family dynamic so its really hard to compare. Sorry this is so long! Would really appreciate some insight.