Kim Petras Says She and Sam Smith 'Cried' Together After Learning 'Unholy' Hit No. 1 on the Hot 100

Kim Petras is opening up about how she learned her song "Unholy" had hit No. 1 on the Billboard Hot 100 chart.

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

"It was a super magical night, and we cried," Petras told PEOPLE at Heidi Klum's 2022 Halloween party — which was presented by Now Screaming x Prime Video and Baileys Irish Cream Liqueur. "It was amazing. We spent it together that night, and I'll never forget it."

"Unholy" made history in 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 previously celebrated the 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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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.

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 powerhouse Max 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.