The Duke of Sussex opens up about his own mental health battle in the series he co-created with Oprah -- "The Me You Can't See -- and he takes viewers back to 1997 when he and his brother, Prince William, were in shock after their mother's death.

Prince Harry says he felt "outside of my body" and struggled processing what happened, but his feelings turned to anger over Di getting no justice. He says, "Nothing came from that. The same people who chased her into the tunnel, photographed her dying on the backseat of that car."

Though he was having a very hard time, Harry claims his calls for help within the Royal Family were met with "total silence" ... and he was expected to carry on. Eventually, he says he just stopped thinking about it because it only made him sad.

Remember, Harry's already said Prince Charles' parenting caused him serious trauma -- and, as a result, royal aides have reportedly suggested Harry should be stripped of all his titles.

This all led to a period of hard-partying from the ages of 28 to 32, which Harry calls "a nightmare time in my life." He tells Oprah he was drinking a week's worth of alcohol on some nights to mask his pain, and was willing to take drugs to make him feel less like he was feeling.

Harry also talks about his relationship with Meghan Markle, who he says first encouraged him to seek therapy about 4 years ago. He says, "I knew that if I didn't do therapy and fix myself, that I was going to lose this woman who I could see spending the rest of my life with."

Meghan, of course, has detailed her own mental health struggles, and Harry talks about the scary night she expressed suicidal thoughts to him while pregnant with Archie ... something they first revealed during their CBS interview with Oprah.