Sophia Bush Says Death of Ex-Boyfriend Dan Fredinburg 'Shattered' Her

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Sophia Bush may play a tough detective on TV, and a lot of that resilience comes from the challenges she's faced in real life.

The Chicago P.D. star is Health's September cover girl, and she opened up to the magazine on the big moments that have changed her views on life forever.

WATCH: Sophia Bush 'Devastated' by Death of Ex-Boyfriend Dan Fredinburg in Everest Earthquake

In April, Bush's ex-boyfriend, Google executive Dan Fredinburg, died of a head injury following an avalanche on Mt. Everest. Four months later, Bush is still reeling from the shocking accident.

"Losing one of my best friends a few months ago shattered me. There were days I felt like my body had been turned inside out," she told Health. "I felt like my heart was on the outside of my body and everyone who came near me was stabbing me."

The heartache, however, has taught the 33-year-old actress to live every day like there's no tomorrow.

"And the crazy thing is that since Dan died, the lessons have come like Mack trucks," she says. "There is no next time. There is no excuse to wait a day to do what you want to do and to change the way that you want to change."

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Upon learning of his death, Bush posted a heartfelt tribute to Fredinburg, whom she dated from April 2013 through February 2014, on Instagram.

"There are no adequate words," she wrote on April 25. "Today I find myself attempting to pick up the pieces of my heart that have broken into such tiny shards, I'll likely never find them all. Today I, and so many of my loved ones, lost an incredible friend. Dan Fredinburg was one-of-a-kind. Fearless. Funny. A dancing robot who liked to ride dinosaurs and chase the sun and envision a better future for the world. His brain knew how to build it. His heart was constantly evolving to push himself to make it so. He was one of my favorite human beings on Earth."

"He was one of the great loves of my life," she continued. "He was one of my truest friends. He was an incredible brother, a brilliant engineer, and a damn good man. I'm devastated and simultaneously so deeply grateful to have known and loved him, and to have counted him as one of my tribe."

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Fredinburg’s death was far from the first difficult experience that has helped strengthen Bush.

"When I was 20, my mom was really sick," she told the magazine. "I watched her go through chemo, and that cracked me. My mother, my everything, the strongest woman I know, was literally on her knees unable to stand, and that shattered me."

Bush explains that "the only way to get out of pain is to go through it," which is how she coped with her mom’s illness and is now dealing with the death of her dear friend. One of the ways she’s handling stress is by leaning on those closest to her. The actress says she feels the happiest when "twenty of our friends are over, we have a great band at my house and we're having long conversations around a fire pit."

And her go-to way to de-stress? "I can't believe it took me 32 years to feel like I deserve to get massages, but a super deep tissue," she says. "Game changer."

WATCH: Sophia Bush 'Devastated' by Death of Ex Dan Fredinburg in Nepal Earthquake