Just ahead of the release of his memoir Spare, Prince Harry sat down for an interview with Anderson Cooper on 60 Minutes. The Duke of Sussex shared how he coped with the loss of his mother, Princess Diana, after she died in a car crash in 1997.

Harry told Cooper that he was in such denial about his mother’s death that he believed she was still alive. “For a long time. I just refused to accept that she was gone. Part of [it was] she would never do this to us. But also, part of it maybe [felt like] this is all part of a plan,” he said. “For a time [I believed she was alive] and then she would call us, and we would go and join her.”

“Many years” went by before Harry could accept that his mother had died. He added that psychedelic and psilocybin mushrooms helped him process his grief. “I would never recommend people to do this recreationally,” Harry told Cooper. “But doing it with the right people if you are suffering from a huge amount of loss, grief, or trauma, then these things have a way of working as a medicine.”

“For me they cleared the wind screen, the misery of loss,” he explained. “They cleared away this idea that I had my head that my mother — that I needed to cry to prove to my mother that I missed her, when, in fact, what she wanted was for me to be happy.”