Tiffany Thornton, Demi Lovato Tiffany Thornton, Demi Lovato

Sonny with a Chance's Tiffany Thornton has confirmed that former co-star Demi Lovato will serve as one of her bridesmaids in her upcoming wedding to court officer Christopher Carney.

"We go way back. She's like a little sister to me. She's one of my closest friends," Thornton tells

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Thornton says she and Lovato have bonded over their faith and shared love of Pinkberry.

On Lovato's recently announced health-related Sonny departure, Thornton says: "I'll miss Demi. I'm really proud of her. It takes a lot of guts to admit that you aren't perfect in front of the world."

Hear Thornton told us about her friendship with Lovato in the video below: