October 4, 2016 3:45 PM EDT

Original American Idol winner Kelly Clarkson made a serious confession to Ellen DeGeneres on Tuesday: she ghosted on a date once when she was 18, and she still feels terrible about. DeGeneres had promised to donate $10,000 to a breast cancer charity if she shared a never-before-heard secret, and Clarkson bashfully came up with this one. Apparently, she had met the date while working as a cocktail waitress, and finally agreed to spend time with him. But it did not go smoothly.

“I withstood an hour,” she told DeGeneres about her second-ever date. “And then I went to the bathroom and I left… I’m going straight to hell, I’m aware. It’s the worst thing I’ve ever done.”

She added a public, years-delayed apology, in case he had happened to tune in to her big confession: “If you’re out there, I’m so sorry. I know I’m a horrible human.”

She added that she tried to amp herself up to say goodbye properly—but chickened out at the last minute.

“Honest to God I had a ‘come to Jesus’ in the bathroom, and I was like, ‘You will go out there, you will put your big girl panties on and do it, and just go out there and just be a good person.’ And I chose to not be.”

As for the nameless stranger, he’s probably been singing “Since U Been Gone” all these years to get over the slight.

Watch the full clip above.

Write to Raisa Bruner at raisa.bruner@time.com.

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