I'm completely in shock and have no idea where to turn!
I'm in a circle of friends of about 6 people. We've been friends since 16 at college. We're not all super close but we meet up (pre-covid) for birthdays, Christmas night out, the occasional girls night etc. But we're older now and have more commitments.
We'll call the 2 friends in question Sarah and Emma for privacy. Sarah is my best friend, she lives on my street, we see each other everyday (pre-covid) and facetime and she's like my right arm. She's also my husbands workmate, she's always told me everything or so I thought.
Emma is a part of the friend group but we're not really close, we wouldn't ever speak other than the general get togethers. But she's still a friend.
Emma has been married for 8 years (we're all 32) we'll call her husband John and they have kids.
I've known Sarah be seeing someone on and off for a couple of years but very casual and she just said it was someone she met in town once. I've never questioned it because she's single and likes to keep everything casual, she's always lived alone and been independent.
I saw John going into Sarah's house last week and when I called her and asked why she instantly told me she's been seeing him for 4 years in secret! It used to be one night every so often but then turned into more regular meet ups. Sarah said they were both agreed it was best that way but since lockdown when John and Emma both went on furlough, he hasn't had an excuse to go see her and they've realised how much they love one another. Sarah said she doesn't expect him to leave Emma yet but she thinks he will one day when things are easier for them.
I'm in total shock. She's asked me not to tell anyone including my husband who she sees at work everyday and she's asked me not to tell Emma, she said she wanted to open up to me but not do anything and just wanted someone to talk to.
I'm so angry at her for doing this to Emma and I'm angry she's told me expecting me to keep this lie for her. I'm completely torn. I want to be there for my best friend but I don't want to put Emma through this any longer when the poor woman has no clue what her husband is up to and for so long!
Please tell me what to do and let me know if I'm unreasonable to think about just telling my friend I want no part in it and pretend I never heard it?