Saoirse Kennedy Hill, granddaughter of assassinated Sen.Robert F. Kennedy and the only child ofCourtney Kennedy Hill, was buried Monday afternoon next to her auntMary Richardson Kennedy — the second wife of Saoirse’s uncle Robert F. Kennedy Jr., who killed herself in May 2012.

“They’ve had so much tragedy in the family that it’s got to be hard for them to reconcile it all,” says family biographer J. Randy Taraborrelli.

“You go on with your life but you carry it, you carry these people and your heart is always broken,” he says.

Saoirse, who had spoken candidly about her years-long depression and the need to de-stigmatize discussions of mental health, was found unresponsive at the Kennedy family compound on Thursday and pronounced dead soon after. She was 22.

She is suspected of overdosing, according to multiple news outlets, though her cause of death is pending a toxicology report. One local who knew her and her mother believes her death was accidental.

“I literally watched her social media stories earlier that day, less than 12 hours before the story broke,” says a friend of Saoirse’s from Boston College, Bill Stone.

“She seemed happy,” Stone recalls but says, “I knew she had her demons. … I knew she struggled with those for a while.” Still, “She tried to have a super positive attitude about the challenges she was facing and tried not to let them rule her.”

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Ina 2016 piece for the student newspaper at her private school, Saoirse opened up about her time in treatment, a previous suicide attempt and her depression, which was already a familiar presence.

“My depression took root in the beginning of my middle school years and will be with me for the rest of my life,” she wrote. “Although I was mostly a happy child, I suffered bouts of deep sadness that felt like a heavy boulder on my chest.”

“People talk about cancer freely; why is it so difficult to discuss the effects of depression, [bipolar], anxiety, or schizophrenic disorders?” she wrote. “Just because the illness may not be outwardly visible doesn’t mean the person suffering from it isn’t struggling.”

Mary, who hung herself at 52 amid a deteriorating marriage with Robert F. Kennedy Jr., struggled with depression before her death.

But while her estranged husband sobbed from the church pulpit at her funeral as he described her “demons,” friend Carole Radziwill told PEOPLE in 2012: “Battling demons? That’s hyperbolic language. I didn’t see anything close to that.”

On Monday, seven years later, Robert delivered another eulogy — this one at Saoirse’s funeral service before her private burial. He describedsome of her final hours: how she spent time with her grandmotherEthel Kennedy and had gone out with a friend before returning home for a sunrise swim in the Atlantic Ocean.

On Instagram, alongside intimate family photos,he wrote last week that she was “fierce, both in her love for her family and yearning for justice. A fearless adventurer, she inspired curiosity and daring in her friends. But her greatest gift was to find humor in everything and to give us all the gift of her laughter — and our own.

“The gaping hole that she leaves in our family is a wound too large to ever heal.”

• With reporting by LIZ McNEIL

If you or someone you know is considering suicide, please contact the National Suicide Prevention Lifeline at 1-800-273-TALK (8255), text “home” to the Crisis Text Line at 741-741 or go to suicidepreventionlifeline.org.