Prince William opened up about the "traumatic death" of his mother, Princess Diana, in a new documentary, Football, Prince William and our Mental Health. Here, the Duke of Cambridge revealed how being a dad made him remember the horrific grief he once experienced after that one fateful day of1997.

In a talk with the soccer player Marvin Sordell, Prince William revealed that when he became a father himself, it brought a lot of feelings about losing his mom at a young age. To recall, Princess Diana died in a car crash on Aug. 31, 1997, when Kate Middleton's husband was only 15.

The future king said that having kids is the "biggest life-changing moment" for him, Hollywood Life noted. He explained that when people had been through something traumatic in their life and their dad was not around and their mother died, their emotions would come back in "leaps and bounds" because it would be a very different stage of life.

Sixteen years after his mother's death, he became a first-time dad to their firstborn son, Prince George. At the time, he felt like there was no one there to help him as he found fatherhood could be "very overwhelming" at times.

Prince William continued that at the time, things would come out of the blue emotionally when he least expected. Although he confessed that having kids is one of the most amazing moments in life, he admitted that it is also one of the scariest.

Aside from Prince George, the second in line to the throne and Kate Middleton also have two other kids, Princess Charlotte and Prince Louis. According to News.com.au, although Princess Diana is now gone, he makes sure his children know about their grandmother.

He continually tells them things about the late Princess of Wales. It is of utmost importance for him that they know who she was and she once existed.

Prince William also praised his wife for continuously supporting him throughout these challenges. He calls the Duchess of Cambridge through her name Catherine, revealing they are showing their support to one another. They go through different moments together that help them evolve and learn at the same time.

His brother, Prince Harry, on the other hand, called the memories about Princess Diana's death as a "wound that festers," Independent reported. So, every time he would see a camera, hear the click, and catch its flash, it would send him straight back to the time that he lost his mother, which he called as the worst reminder of his life. Prince William's Football, Prince William and our Mental Health will be out on May 28 on BBC.