Sandra Bullock Found Out About Husband's Alleged Infidelity From Publicist, Report Says

Sandra Bullock found out about her husband Jesse James' rumored infidelity from her publicist after InTouch magazine called to say they would soon be running a story that he was cheating on her with a tattoo model.

According to a report from, In Touch called Bullock's publicist Monday morning to let her know that Michelle 'Bombshell' McGee had confessed to a months-long affair with Sandra Bullock's husband Jesse James while Bullock was filming "The Blind Side" in 2009.

In Touch closes its issue Monday night to go to print Tuesday, a former tabloid editor tells Weeklies typically give celebrity publicists 24 hours to respond to a report of such magnitude, so Bullock would likely have been notified Sunday night or Monday morning at the latest.

By Monday afternoon, Bullock had moved out of the home she shares with James. Just days later, the shocking claims from the tattoo model were released to the public.

McGee told In Touch magazine she and James had sex repeatedly while Bullock was shooting "The Blind Side," the film that earned her an Oscar.

More On This...

PHOTOS: More of Michelle 'Bombshell' McGee.

She told the magazine she thought James and Bullock were separated.

"I would never have hooked up with him if I thought he was a married man," she said.

Following the revelations, Bullock issued a statement saying she was canceling her appearance at the London premiere of "The Blind Side."

FOX411: Is 'Bombshell' some sort of leather-clad Doogie Howser?

"Due to unforeseen personal reasons a trip abroad to support 'The Blind Side'  has been deemed impossible at this time," Bullock said in a statement. "I apologize for any inconvenience this may have caused and thank you for your continued support of the film."

FOX411: The 'smoking gun' texts McGee offered as proof of affair.

James also deleted his Twitter account Wednesday. He had recently used his account to publicize his lost dog, Cinnabun, who was later found before disappearing again Monday.

Meanwhile, James apologized to Bullock and his children Thursday, saying his "poor judgment" brought his family "embarrassment beyond comprehension."

Bullock won the Academy Award for Best Actress for her role in 'The Blind Side.' In an interview with Barbara Walters before the Oscars ceremony, she said of James, "I’d never before met a man who I felt had my back."

SLIDESHOW: Sandra Bullock Was On Top of the World.

But McGee said that while Bullock was in Atlanta working on the movie, she had sex at least once a week with the "Monster Garage" star.

McGee said she originally reached out to James because she wanted to get a modeling job at his company West Coast Choppers. She said she was surprised when he responded and asked her to send photos to his personal e-mail, In Touch reports.

She said she drove to meet him at his office, where she asked him about Bullock.

SLIDESHOW: Is There an Oscar 'Couple Curse'?

"He said, 'She doesn't live here. She has a house in Austin. She is filming, and I can't talk about it,'" McGee told the magazine.

She said they had sex several times in the weeks that followed.

Before marrying Sandra Bullock in 2005, Jesse James was married to porn star Janine Lindemulder, with whom he is now in a custody battle over their young daughter.

Follow Fox411 on Twitter for updates.