Prince Harry has written an open letter to grieving children, sharing that the death of his mother Diana, Princess of Wales, left “a huge hole inside of me.” The 36-year-old royal wrote the passage for the book Hospital by the Hill by Chris Connaughton, which according to its website, is for “children and young people bereaved by the COVID-19 pandemic.” The book will be published on March 23 on National Day of Reflection, a UK holiday that supports people who lost loved ones. Connaughton told E! of Harry’s contribution, “I wanted it to provide a connection, support and hope through the hard and horrible times of bereavement. It’s also a tremendous honor—and a service to young people—to have The Duke of Sussex support this project and share his open, heartfelt and honest words with kids across the country.” In the forward, obtained in full by Town & Country, Harry writes in part, “When I was a young boy I lost my mum. At the time I didn’t want to believe it or accept it, and it left a huge hole inside of me. I know how you feel, and I want to assure you that over time that hole will be filled with so much love and support. We all cope with loss in a different way, but when a parent goes to heaven, I was told their spirit, their love and the memories of them do not. They are always with you and you can hold onto them forever. I find this to be true.” Harry added, “You may feel alone, you may feel sad, you may feel angry, you may feel bad. This feeling will pass. And I will make a promise to you – you will feel better and stronger once you are ready to talk about how it makes you feel.” In 1997, one year after her divorce from Prince Charles, Diana died in a car accident at age 36 in Paris, France, while being chased by photographers. She left behind two sons, Prince William, then 15, and Prince Harry, then 12. Both men have spoken about the trauma of losing their mother, as recent as this week. On Mother’s Day, which in the UK falls on March 14, Harry lay flowers at Diana’s gravesite in Northamptonshire, according to royal expert Omid Scobie. And William and his wife Kate Middleton, 39, tweeted drawings addressed to “Granny” Diana, from their children Prince George, Princess Charlotte and Prince Louis.