This week's issue of PEOPLE takes an in-depth look at the rise of suicides among K-pop idols and speaks to former f(x) group member Amber Liu

Amber Liu knows firsthand that the fun and excitement of K-pop — a genre which has exploded in the U.S. in recent years thanks to groups like the electrifying boy band BTS — can belie a darkness that has driven some performers to despair.

“It was fun at first,” the former member of the South Korean girl group f(x) tells PEOPLE in this week’s issue, on newsstands Friday. “But later the loneliness and all that stuff settles in.” Last year a number of K-pop idols took their own lives, including Liu’s former bandmate Sulli, who was 25 at the time of her death. The types of struggles they once experienced in the glare of the global spotlight, are ones to which Liu herself can attest.

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Born and raised in Los Angeles, Liu, now 27, got her start in the K-pop industry after being scouted by one of South Korea’s largest entertainment companies, SM Entertainment, at a festival in Koreatown at the age of 15. Several successful auditions later, she packed her bags and moved to South Korea on March 1, 2008.

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The next year and a half Liu would spend balancing a grueling training schedule and the pressure to please at SM Entertainment’s trainee school before debuting with bandmates Sulli, Krystal, Victoria and Luna as the multinational girl group f(x) in 2009. (SM Entertainment has not responded to PEOPLE’s requests for comment on this story.)

“Of course I’m going to post happy things on social media,” Liu says. “Because if I post that I’m depressed, nobody’s going to want to see that.”

For more on the heartbreaking stories of recent K-pop suicides and Amber Liu’s journey, pick up this week’s issue of PEOPLE on newsstands Friday.

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When Liu learned that her bandmate Sulli, who left f(x) in 2015 to purse an acting career, died by suicide at the age of 25 on Oct. 14, 2019, her first feeling was disbelief — then anger.

“It was just so hard,” Liu says. “I felt really angry. I was angry at myself, too, because Sulli and I talked a few weeks before. It’s like, ‘Man, if I just sent another text, what could have happened?'”

Known for speaking out about her feminist ideals, Sulli often received backlash from her contemporaries in conservative South Korea, particularly for going out in public without a bra.

“She was so brave and so bold and really fought for women’s rights in a way that no other celebrities in Korea had yet,” says American filmmaker Kelley Katzenmeyer, who has lived in Korea for 10 years and is working to erase the stigma surrounding mental health in the country through her documentary, Permission to Exist. “It was really hard when she passed.”

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Throughout the six years they spent together in f(x) between 2009 and 2015, Liu says Sulli “wasn’t that type of person to actually let things get to her.” But one of the last Instagram Live videos she’d share before her death, in which she told her followers, “I’m not a bad person,” showed the toll the online hate was taking on her.

“We grew up learning that sticks and stones may break my bones but words will never hurt me, but words do hurt,” Liu says. “They physically can hurt.”

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Just a month after Sulli’s death, her friend and fellow K-pop idol Goo Hara — who was a member of the band Kara and was outspoken when it came to defending herself against online harassment — was found dead by suicide in her home at the age of 28.

Less than two weeks later, actor and singer Cha In-ha of the group Surprise U was found dead in his home at the age of 27. (His death has not yet been ruled a suicide.) And two years prior, Jonghyun — the longtime lead vocalist of the group SHINee — died by suicide at the age of 27 and left a note that read: “I am broken from inside. The depression that gnawed on me slowly has finally engulfed me entirely.”

At the height of f(x)’s fame, Liu says she was “going on fumes.”

“You’d literally wake up, go to a job, go back to sleep in the car and drive to the next job,” she says. “We were grinding.”

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The burden of fame and the quest for perfection felt insurmountable. “We honestly talked more about diets than music … We were taught to starve,” Liu says.

At the time, Liu says, she had “the worst relationship with food,” sometimes drinking only a can of Coca-Cola a day. The group’s “tomboy,” she didn’t fit the mold of the typical doe-eyed, feminine K-pop idol and would get nasty comments online from people about everything from her sun-kissed California skin to her pixie cut, like, “How is she going to get married with short hair?”

“I didn’t realize how much these comments actually hurt me,” Liu says. “I am now a lot more open with my friends, and this actually helped me out a lot.”

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Once, Liu says she even considered plastic surgery.

“I thought I really did need it,” she says. “Luckily Krystal talked me out of it. She was like, ‘Amber, you don’t need it. You don’t need it.’ We’re told that we need these things when we actually don’t. Our bodies are still developing.”

Seoul, South Korea’s capital, has the highest plastic-surgery rate per capita in the world.

“In the subways in Seoul, there are plastic surgery ads everywhere,” Katzenmeyer, 28, says.”To girls in Seoul, beauty standards are as important as their academics.”

Now a successful solo artist, Liu (who recently wrapped her X tour) is still working through the physical and emotional pain of her past.

“It took years for my body to rehabilitate,” she says, adding that she has experienced anxiety on a “different level” the past couple of years and is now in therapy. “It’s to a point that I know that I need to start taking care of my mental health. I’m working hard every day to try to figure it out,” she says.

As she looks toward the future, Liu is proud of her connection with her fans.

“I’m extremely happy to be part of someone’s healing process,” she says. “All I want to do is keep working hard, and create music that will brighten somebody’s day.”