Christie Brinkley Attends Ex Billy Joel's Show
07/19/2008 AT 12:00 PM EDT
After spending the Fourth of July at Joel's Sag Harbor, N.Y., house, Brinkley attended his "The Last Play at Shea, From the Beatles to Billy" concert at New York's Shea Stadium Friday night. (It's the last concert at the ballpark and the last season for the New York Mets, who move into a new home at Citi Field in 2009.)
At the show, Brinkley seemed to enjoy the support of Joel's fans, who clapped for her as she walked by. "Everyone was yelling good job to her as she walked through the stadium," an onlooker tells PEOPLE. "She was so nice and sweet, saying thank you back to people."
Brinkley watched Joel sing just a few rows back from the stage with a female friend and her daughter Alexa, 20, a source says.
"She was having the best time singing to the music," the witness adds.
Brinkley even took the time to pose for pictures with fans before and after the show.
Says the onlooker: "She was smiling so much."