Britney Spears put abuse rumors to rest when she visited beau Jason Trawick at work in L.A. Wednesday.

Earlier that afternoon, the Spears' reps denied that Trawick, 38, beat the singer, calling reports by tabloid Star and RadarOnline "laughable" and "utterly false."

With her hair tucked under a fedora, Spears, 29, joined Trawick at the William Morris Endeavor Entertainment offices for a special screening of The Secretariat on behalf of Hathaway Sycamores, the largest provider for children's mental health services in L.A. County.

"They were both very upbeat. They were smiling and seemed very happy to be there," Rob Myers, executive vice president of development at Hathaway-Sycamores, tells

After the couple greeted the families and introduced the film, "the buzz in the room was fantastic," Myers says. "The look on the children's faces was just priceless."

And despite the allegations against him, Trawick showed little signs of worry during Spears' surprise appearance.

"Jason was obviously having a tough day, but he kept his commitment to bring Britney in to the screening," a source tells Us. "He acted professional at all times despite the false story."

"It's amazing that Star continues to try to defend their story by putting out more and more pieces of a fraudulent recording. Everyone knows it is not her," Spears' manager Larry Rudolph tells Us. "The more they put out, the more ridiculous they look. The lawyers are drawing up the legal papers right now; there will 100 percent be a lawsuit. We are suing."