Jamie Lynn Spears cheated on Casey Aldridge

Jamie Lynn Spears cheated on her boyfriend Casey Aldridge - even after finding out she was pregnant, according to a bombshell new report from the US.

The 16-year-old 'Zoey 101' star partied in her hometown of Kentwood, La. and begged a guy at the party for sex, American magazine Star claims.

"It's cool, I'm pregnant," she told him. "I can't get pregnant again!"

And it was not the first time. "I know for a fact that Casey was not the first guy she slept with — or the last," says one fellow teen in Kentwood, La. "There were at least two others. I know that 110 percent."

Another friend claims that before her pregnancy, Jamie Lynn partied hard but always in private. "Some people drink to have a good time. But she drank to get wrecked," said the friend. "She drank to get messed up and forget about her mother, her sister and all of that."

The actress - the younger sister of troubled pop star Britney Spears - has also accepted she may never return to her glamorous life in Hollywood. Instead she and Casey have  decided to keep the baby -- and even buy a double-wide trailer to start their lives together.