I thought that Charles did tell Di that he had been in love with Cam, that she was still a good friend but that now, he loived her.(ie Diana). I simply cant beleive she didn't know.. Unless she lived in a cave, didnt' read the gossip columns or talk with anyone in her circle, where there was plenty of gossip about his close relationship with CPB... She must have known that Cam was a past girlfriend..I mean during her courtship, she was staying at Cam's house, Did she think that it was a hotel? She must have known that she was invited there because Cam was Chas' ex and good friend and was willing to host his current girlfriend...