My dept at work has one boss and I am his right hand woman- he often discusses things with me despite my not officially being in a management role vis a vis our more junior team members (I'm up for promotion very shortly). So far, so good.
We'd been having performance issues with one woman, so boss asked if I'd take her out to lunch to try to get to the bottom of why she wasn't coming up to scratch, particularly as he'd had to be quite harsh with her and their communication was deteriorating. So I arranged that for Thursday.
Then today she did something that was the straw that broke the camel's back for him, so he have her her notice. However he told her it would be totally confidential and nobody else in the team would know, so she could just pretend she had found another job. And now I have to go ahead with the lunch (which I described as being so I could have a chat about how she was getting on generally, as seniors are supposed to do that for juniors anyway). If I cancel she'll know that I know, but it's going to be a total charade. It would be totally U to tell her I know, wouldn't it?