British superstar Adele said she cried all day after what was supposed to be a triumphant return to the Grammys stage turned into a shaky live performance in which she sang off-key. "I was so embarrassed," the "Someone Like You" singer told U.S. talk show host Ellen DeGeneres in an interview recorded on Wednesday. "I cried pretty much all day yesterday," said Adele, a six-time Grammy winner in 2012. Monday's Grammy Awards marked the biggest appearance for the 27-year-old singer in four years.