Photo: Christopher Polk/Variety via Getty Images

Sam Smith and Kim Petras during night one of the iHeartRadio Music Festival

Kim Petrasis opening up about how she learned her song “Unholy” had hit No. 1 on theBillboardHot 100 chart.

The German-born singer, 30, revealed that she andSam Smithwere together in London the night they found out their collaboration had topped the U.S. music chart.

“Unholy"made historyin October when it earned the top spot on the Hot 100 chart. Smith, 30, became the first-ever openly non-binary solo artist to achieve the feat, while Petras became the first openly transgender solo artist to do so. Earning the No. 1 spot was “insane,” Petras said.

She previouslycelebratedthe accomplishment, writing in a prior Instagram post that she was “honored to be part of” Smith’s first No. 1 in the U.S., which she said he should have “500 of at this point.”

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David M. Benett/Dave Benett/Getty Images

Kim Petras (L) and Sam Smith attend the Harris Reed September 2022 Show during London Fashion Week September 2022

Petras said her collaboration with Smith was “four years in the making,” explaining: “We’d been sending songs back and forth [for years], and it’s amazing.”

“But still, I feel like, for something to go No. 1, it’s so much luck and just crazy stuff,” she continued. “I’m from the middle of nowhere in Germany, and I came here eight years ago as a songwriter. I didn’t think I could be an artist.”

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Petras also noted that she’s “so grateful” to have this achievement under her belt after working “so hard to get to this point”

“To work on stuff for the last five years, and just [having] released so many songs and [previously] been independent, I’m grateful that people are recognizing I’ve worked really hard,” she said.

Christopher Polk/Variety via Getty Images

Kim Petras during night one of the iHeartRadio Music Festival

Next up, Petras is gearing up for the release of her follow-up single, “If Jesus Was a Rockstar,” which is due to drop on Nov. 11.

Co-written with pop powerhouseMax Martin— whom Petras calls “one of my heroes” — the “Heart to Break” crooner said she isn’t slowing down any time soon with her forthcoming releases.

“I’m not stopping now. I feel like I’ve reached this new plateau,” she told PEOPLE. “And now the pressure’s on for the songs to do well, and I feel ready.”

“I have songs backed up, so many songs, that I feel are really ready [for public consumption],” Petras added.

“If Jesus Was a Rockstar” will be available to purchase and stream on Nov. 11.

source: people.com