Long time lurker, a few posts but NC for this.
DH and I are mid-60s, professionals, no children (by choice). Generally content, or so I thought.
He went into work at the weekend, which was a little unusual but he works in a hospital - they have been so busy lately and he said he wanted to 'get caught up' with work so I thought nothing of it. This afternoon however I got an email from a colleague of his - she's sort of a friend of ours as she's worked with him for years but we're not close friends or anything. She said that she'd gone in on Sunday to catch up on work and seen DH kissing someone in his office and that she thought I ought to know. I immediately rang her and she was very cagey - said that as DH and her work together she didn't want him to know that it came from her but again that 'I ought to know'.
I managed to drag out of her that this woman is a colleague of theirs, mid-40s, also married, with a son. When I pressed her for more details she admitted that she had had suspicions about the two of them as long as 2 years ago when they all went to a conference - she thought they were acting strangely but couldn't confirm anything so didn't tell me!
Has he been having sex with this woman for 2 years?! Or if they were only kissing does that mean that this is as far as it's gone? I am livid and sick and devastated and don't know what to do. I've looked up OW on social media, she's dark haired and slim and pretty and just his type 
I was thinking of getting in touch with the line manager of the OW and telling them that she's been having an inappropriate relationship with a colleague, and doing the same with my DH line manager. I would ask them to keep it anonymous so they wouldn't know it came from me or DH colleague. Please don't tell me to LTB I'm 64 and I just can't start again on my own. I just want them both to suffer a bit, I can't think what else to do.