The duke told US talk show host Winfrey his family did not speak about Diana’s death and expected him to just deal with the resulting press attention and mental distress.
The Princess of Wales died in a car crash while being pursued by photographers in Paris in August 1997.
The duke told Winfrey that he used to drink a week's worth of alcohol in a day to try to deal with the trauma of his mother's death.
Harry also said that when he tried to get assistance from his family with the attacks levelled at him and his wife, Meghan Markle, online, that “every single ask, request, warning, whatever it is, to stop just got met with total silence or total neglect.”
“We spent four years trying to make it work. We did everything that we possibly could to stay there and carry on doing the role and doing the job,” he added.
The duke said he did not go to his family when Meghan felt suicidal because he was ashamed the situation had gotten “that bad”, and also suspected the royals would not have been able to help.
He said: “That was one of the biggest reasons to leave, feeling trapped and feeling controlled through fear, both by the media and by the system itself which never encouraged the talking about this kind of trauma.
“Certainly now I will never be bullied into silence,” Harry added.
‘The only way to free yourself and break out is to tell the truth’
The duke also addressed his relationship with his father, the Prince of Wales, as he said: “My father used to say to me when I was younger, he used to say to both William and I, ‘Well it was like that for me so it’s going to be like that for you.’”
“That doesn’t make sense. Just because you suffered doesn’t mean that your kids have to suffer, in fact quite the opposite – if you suffered, do everything you can to make sure that whatever negative experiences you had, that you can make it right for your kids,” he added.
Harry said his family told him to “play the game” and life would improve, but told Winfrey that he’s got “a hell of a lot of my mum in me.”
“The only way to free yourself and break out is to tell the truth,” he added.