Princess Diana died in that tragic car accident 20 years ago, but her sons Prince William and Prince Harry can still recall what it was like when they first heard the life-changing news. The brothers open up about that fateful moment in a new clip from Diana, 7 Days, an upcoming documentary that follows the late royal's final days."I remember just feeling completely numb, disorientated, dizzy," Prince William said, according to a report from Good Morning America. "You feel very, very confused," William added. "And you keep asking yourself 'Why me?' All the time, 'Why, what have I done? Why, why has this happened to us?'"William and Harry were vacationing at Balmoral Castle, the royal family's holiday residence in Scotland, when their father Prince Charles broke the news. They were only 15 and 12, respectively, at the time. The Queen decided to let them stay at Balmoral to grieve in private rather than return immediately to Buckingham Palace and be under the public eye. People criticized Her Majesty for the decision, but William and Harry praised their grandmother for putting her family first."I think it was a very hard decision for my grandmother to make," William said. "She felt very torn between being a grandmother to William and Harry and her Queen role." Harry added, "It was a case of 'How do we let the boys grieve in privacy, but at the same time, when is the right time for them to put on their prince hats and carry out duties?'"The princes were also grateful for their father Prince Charles' comfort, even though he was also hurting. "He was there for us and he tried to do his best and to make sure we were protected and looked after," Prince Harry said. "But, you know, he was going through the same grieving process as well."In the preview, the brothers also share their anger over the paparazzi for photographing their mother's dying moments instead of offering to help, and explain how they learned to cope with the loss as they resumed their public duties."When you have something so traumatic as the death of your mother when you're 15—as, very sadly, many people have experienced and no one wants to experience—it'll either make or break you," William said. "And I wouldn't let it break me. I wanted it to make me."