Just days after Katharine McPhee was caught kissing her married former "Smash" director, Michael Morris, a source revealed to US Weekly that the singer and actress is feeling "embarrassed" over the current scandal involving photos of the two smooching outside after a lunch date.

"She is SO embarrassed she was caught," a source told the gossip magazine. "She should have known better!"

Though McPhee herself is also married, she has been separated from her husband, Nick Cokas, for at least six months, and the two have been living separately. Morris, however, is married to actress Mary McCormack, who allegedly has kicked him out of the house last week. The two share three young children together and reportedly split their time between L.A. and New Mexico, and have been married for 10 years, but McCormack may soon be seeking a divorce.

According to Page Six, Morris allegedly tried to buy the paparazzi photos of the two kissing in order to avoid the public scandal.

As for how the fallout will affect McPhee's career, Jamie Krauss, PR director at the Narrative Group, told FOX411 that her "likability factor will be seriously tarnished," though with so many celebrities having been caught in cheating scandals, including Kristen Stewart's affair last year with then-married director Rupert Sanders, it may soon wash over and not leave any lasting effects on her image or sales.

"Katharine McPhee having an affair with this director, this sort of thing usually helps someone's career in this day and age," Maxim TV director Ken Shadford said on his website. "Just this side of a sex tape, getting in the scandal sheets is sort of the way to go to help your career." 

Click here to see the kissing photos.