“I think the memory that I’ll always first have of Christina [Aguilera] is when I walked up to her, she screamed,” Demi Lovato told PEOPLE

Demi Lovato and Christina Aguilera rocked the 2018 Billboard Music Awards on Sunday night with a soaring performance of their new duet, “Fall in Line.” Though Lovato tweeted “BUCKET LIST ITEM 1”, about collaborating with Aguilera, she came to find out that her favorite ex-Mouseketeer was just as excited about working with her.

“I think the memory that I’ll always have of first meeting Christina is when I walked up to her, she screamed,” Lovato told PEOPLE at the launch of her new summer capsule collection with Kate Hudson’s Fabletics on Friday. “And I was like, ‘I’m the one that should be screaming. It’s you.‘ And she was like, ‘I’m so excited to meet you!’ Just, like, over the top in the most innocent, purest way possible.”

Their collaboration may have been Aguilera’s team’s idea — the track will be featured on her upcoming album Liberation — but this duet has “been a dream” since Lovato “was a little girl.”

Billboard Music Awards, Show, Las Vegas, USA - 20 May 2018

ROB LATOUR/SHUTTERSTOCK
 

“Being able to work with her was literally a dream come true,” Lovato said. “She’s the sweetest woman — just so gracious. She was so excited when I showed up to the shoot. It was great.”

Lovato didn’t miss a beat onstage during the performance, but her moves — and her shoe selection — have been limited after she broke her foot while on vacation in Bali earlier this month.

“I’ve been wearing a sandal and a sneaker, and that’s pretty much all I’ve been wearing on my feet,” she explained. “I had to wear heels in a music video that I just shot. So I had to stuff my broken foot in a heel, but I made it work.”

Demi Lovato, wearing a white top visits Fabletics at The Village at Westfield Topanga, California.

ARI PERILSTEIN/GETTY

When it comes to her wardrobe, Lovato wants the rest of her body to feel as comfortable as her feet, which was a priority when she designed her fourth capsule collection for Fabletics.

“What I wanted to accomplish with this collection was to create more comfortable pieces that will look cute in your daily routine,” she says, “whether it’s running errands or working out.”

The new collection is inspired by Lovato’s “everyday life” on her Tell Me You Love Me world tour and features sports bras, high-waisted leggings and cropped tops in rose, pewter and moss colors.