Taylor Swift knows what it's like to have friends turn their backs on her, PEOPLE reports.

Taylor Swift had Mean Friends

"It happened to me when I was in seventh grade," the country singer, 18, tells Seventeen in the June issue. "I'd been best friends with this group of girls for as long as I could remember, but all of a sudden, they were cool and I wasn't anymore."

"I didn't look as cool or act as cool as they did, and I couldn't figure out why they didn't want to hang out with me anymore," she says. "And that was really sad, to sit there and wonder, 'What's wrong with me?"

"I made this goal sheet when I was like 14 or 15, and it was like, 'My life would be complete if ... I win a CMA award, have a platinum record, have a number one song," she says. "So as I'm checking these things off the list, I'm like, 'You’re kidding me!' "