The singer has made a habit of getting all emotional as she belts out the 2015 track she co-wrote onstage, but she insists the "tough" song is no longer about bad things in her life.

"My father passed away, like, months ago, so it's kind of evolved into this different thing for me too," she tells Access Live. "Now, when I tear up it's, like, for a different reason."

She adds, "It's just a really hard song for me."

At a recent concert in Greenville, South Carolina, Kelly's husband, Brandon Blackstock, thought it would be fun to mess with her by joining her onstage for a performance of the track.

He casually walked out onstage and switched places with her guitar player, just after Kelly assured fans at the show no one was going to make her cry.

"He didn't have in-ears (monitors) in, so he didn't know what I'd just said," she recalled of the moment. "I was like, 'Nobody is gonna mess with me on this song...' and the whole band was like, 'Oh no...!'

"I was crying but at the same time I was floored that he had the nerves to do it. He doesn't usually do that."

The singer, who shares two children with Brandon, smiled and shook her head, before becoming emotional at the gig. After a brief pause, she resumed the song and upon its completion, she leaned in to give her husband a kiss.

"That's my amazing husband, give it up for Brandon," she told the crowd.

Kelly also reflected on the touching surprise during the A Minute & A Glass of Wine segment of her show, during which she admitted she was already on the verge of tears as she brought the tour to a close.

"I'm so sad. This is our last show," she said. "Here's to literally my favourite tour, totally gonna cry. My husband just totally surprised me playing a faux guitar on Piece By Piece and I lost my mind in the tent back there (backstage)."