Prince William spoke out about the death of his mother, Princess Diana, on Thursday night in London as he became the royal head of the Child Bereavement Charity, which his mother used to preside over. "Losing a close family member is one of the hardest experiences that anyone can endure," William told the group. "Never being able to say the word 'mummy' again … it's now really just a word – hollow and evoking memories." The Princess of Wales died in a car crash in Paris 12 years ago when the prince was just 15 years old. (Photo: WENN)