Kelly Clarkson is opening up about her "embarrassing," tear-soaked performance of "Piece by Piece" on American Idol last week - and pointing fingers at 20-month-old daughter River Rose .
"I didn't realize it was gonna be that bad," Clarkson tells Ellen DeGeneres on Thursday's episode of Ellen .
Clarkson, the original American Idol winner, sang during her stint as a guest judge on the series' final season.
The 33-year-old says part of her emotional response was due to the nostalgia factor: "My 1-year-old is running around the same hallway as I was [at] 19."
Clarkson's pregnancy  with her and "great husband" and "great father" Brandon Blackstock 's second child  - a son - also played a role.
"River is constantly watching Finding Nemo ," says Clarkson, adding to the host, "I feel like we live together, you're always in my house."