An interview with Princess Diana has just surfaced in which she reveals the “most awful thing” that happened right before the  five-week royal tour taken by her then-fiance Prince Charles on March 1981.

Diana was seen crying as he departed, and many assumed she was sad that she would have to spend time apart from Charles.

“We have never seen such a touching farewell,” one official said, with another woman who was present at the time saying, “Lady Diana looked really heartbroken.”

However, in a newly surfaced interview, Diana revealed the real reason behind her tears, and it involves Camilla Parker Bowles.

“You may recall seeing a picture of me sobbing in a red coat when he went off on his airplane,” Diana explained. “That had nothing to do with him going. The most awful thing had happened before he went.”

“I was in his study talking to him about his trip,” she continued. “The telephone rang, it was Camilla. Just before he was going for five weeks. So I thought, ‘Shall I be nice or shall I just sit here?’ So I thought I’d be nice, so I left them to it. And it just broke my heart, that.”

Diana also talked about how Charles’ affair with Camilla destroyed her marriage.

“I was still too immature to understand all the messages coming my way,” she said. “And then someone in his office told me that my husband has had a bracelet made for her. I walked into this man’s office one day and I said, ‘Ooh, what’s in that parcel?’ And he said ‘Oh, you shouldn’t look at that.’ So I opened it and there was the bracelet.”

“I was devastated, and I said ‘Well, he’s going to give it to her tonight,'” Diana added. “So rage, rage, rage. You know, ‘Why can’t you be honest with me?’ But no, absolutely cut me dead.”

“It was as if he’d made his decision, and if it wasn’t going to work, it wasn’t going to work,” she concluded. “He’d found the virgin, the sacrificial lamb – and in a way he was obsessed with me, but it was hot and cold, hot and cold, you never knew what mood it was going to be, up and down, up and down.”

Diana and Charles divorced in 1996, and she was killed in a car crash exactly 21 years ago today. Charles went on to marry Camilla in 2005.