I was very very good friends with someone in the past (more than ten years ago): we spent millenium new years eve together in a small group, I cooked the meal for her hen party, I was one of the first people she told when she was pregnant etc. We had a big circle of mutual friends including two of her sisters, both of whom I was close to. Her husband was always a bit 'off' with me, and then 10 years ago she came to me and said we could no longer be friends as she 'knew' what had happened between her dh and me. Turns out he had said that I had asked him to have sex with me ('do you fancy a shag' was the exact wording). This was so unlikely that when I told my dh he just laughed. I found it sort of funny but deeply upsetting that someone could just make up something about me, and it had pretty horrible repercussions (read on!).
I was so appalled and confused that my dh contacted him to talk it through and tell him he must have been mistaken (he cited a time and place that it happened which would have been impossible as I wasn't even in the country at the time). Anyway, the other man pretty nastily kept contacting my dh to insist it was true. His contact with my dh became pretty weird and my dh ended up changing his email address and blocking this person on his phone. I decided to let it go as my dh was getting really incensed about it and not sleeping and it felt like there was nothing much we could do.
Thankfully my dh knew there was no way it could have happened, although I hate to think what might have happened if he had believed it. Although it was clearly a pretty outrageous lie, the friend and her extended circle stopped being friends with us and that was that. I tried to talk it through with one of the sisters who just said that family loyalties had to come first, and the friend's BIL who I had been very close to for years (he is how I met them in the first place) told me that this guy was completely arrogant and may have told the lie to his dw in an argument that then got out of control.
Well the upshot was I lost a whole circle of friends due to the 'family loyalty' but I got over it eventually with time and am fine now. I never saw the couple again. BUT it eats away at me that this man could come up with such an outrageous lie and attempt to mess with my marriage in this way as well as ride roughshod over my friendships let alone my feelings. I really feel like writing to him or his wife and telling them that. It has arisen again as next September my ds is likely going to be going to the same school as their dcs and I am worried about running into them. AIBU to contact them or AIBU to be concerned about my ds going to that school to the extent that now I'm wondering about finding another school for him? It seems so unfair that this one person's mindless actions might continue to have such an impact on my life.