Princess Diana’s brother, Charles, opens up about his biggest regret following her sudden death

It’s been 20 years since Princess Diana’s death and Charles, 9th Earl Spencer and Diana’s younger brother, still has regrets.

According to PEOPLE, Charles was haunted by his sister’s death and felt like he could have done something to prevent it in the days after the tragedy.

“I was furious, I wasn’t just angry,” he said. “[I thought] what could I have done. But you always think, God, I wish I could’ve protected her. It was just … it was devastating.”

“I always felt … intensely protective towards her.” he said.

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In the years since her death, Charles said her memory lives on through her sons, Prince William and Prince Harry.

“I love seeing the sort of uncomplicated way that they deal with people, and put them at their ease,” he said. “It’s so easy to connect the dots between them and their mother.”

“I love the fact that there’s still such veneration inside her immediate family for what she was, and what she meant,” he continued. “I think that’s fantastic.”

Despite the fact that her memory has lived on through her sons, Charles said he does feel upset when he remembers that Diana will never know her grandchildren, Prince George and Princess Charlotte, calling it “one of the great tragedies” of the situation.

“The Story of Diana” airs on ABC on August 9 and 10 at 9 p.m. ET.