When it comes to royal scandals, nothing could get more appalling than Prince Charles’ affair with Camilla Parker-Bowles while he was still married to Princess Diana. While their divorce did not happen until 15 years later, Princess Diana had long discovered that her husband had been cheating on her — in fact, even before they tied the knot.

Princess Diana and Prince Charles married in the summer of 1981. Their fairytale romance had everyone in the world giddy over photos and videos of them together at the St. Paul’s Cathedral on their wedding day. But what everyone didn’t know was that weeks before their wedding, Princess Diana accidentally stumbled upon a personalized bracelet that her husband-to-be was about to give to Camilla. The bracelet had engraved letters on them — G and F, referencing to Prince Charles and Camilla’s nicknames for each other, Gladys and Fred.

All along, Princess Diana knew that Prince Charles was unfaithful to her. But why did she choose to push through with tying the knot? She loved him, and she thought they could manage to make it work.

In an interview following their split in 1996, Princess Diana recounted that devastating moment when she learned about Prince Charles’ affair with Camilla. “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,’” she continued.

When she opened the parcel, she found a bracelet. She knew he was going to give it to Camilla later that night. Enraged, she asked the prince why he could not be honest with her. But Prince Charles cut her dead and told her if it wasn’t going to work, then it wasn’t going to work. At that point, everything was already set for the wedding, and Princess Diana knew there was no turning back.

Prince Charles and Princess Diana ended their marriage in 1996. In April 2005, Prince Charles married his long-time sweetheart Camilla in a civil ceremony at the Guildhall in Windsor.