Diana was loyal to Charles and very discreet about their marriage and complicit in keeping the happy family image going, until it was clear that he was never going to give up Camilla.
Remember that in the Tampon tapes, a large part of the conversation, the bits that are funnily enough not often broadcast or printed, concerned a lot of discussion between Charles and Camilla about the logistics of when and where they were going to meet, thanks to the hospitality of friends, and how they were going to keep this information secret from Diana.
So everyone in royal circles knew the details about affair, including Palace and Highgrove staff, except Diana herself, which is a pretty grim scenario if you think about it.
Diana manipulated the press and wrote the book partly because she believed Martin Bashir’s 70 plus pieces of faked evidence, partly because she was in reality being briefed against by Charles ‘ friends, and partly because she had witnessed her own mother lose custody of her four children in a bitter divorce battle when she had fought against the establishment and the establishment closed ranks against her.
Frances Shand Kydd was thereafter described as “a bolter” but she always insisted she had been forced to give up her dc.
So Diana was very wary of the same thing happening to her, especially when her dc were the heir and the spare and she was up against one of the most powerful family’s in the land. Not exactly the perfect recipe for “peace of mind’, so she knew she had to go nuclear or go home, and put her side of the story.
As for the Squidgy tapes, according to Tina Brown’s book, until his dying day the radio ham who recorded them, said he made the recording on Jan. 4, 1990, four days after the conversation likely took place. And the company Cellnet has said that he could not have made the recording on their airwaves in January since they had not yet built a base in the area. (Outside experts confirmed Cellnet’s claim.) Brown cites several experts who argue that Diana’s phone was bugged and speculates the recording must have been replayed over the air in hopes a civilian would pick it up. So it’s possible that Diana’s so-called “paranoia” was not entirely unfounded.