EXCLUSIVE: Inside Britney Spears' Downward Spiral — Troubled Singer Sparks Concern After 'Out of Control' Driving Incident Following Night Out

But Red O's general manager, Oliver Wynn, insisted Spears was not drunk. He said she only ordered "a quesadilla and no alcohol." Although a fan brought a glass of wine to her table, she "was not intoxicated."

The outing came the day after the release of her ex-husband Kevin Federline's memoir, You Thought You Knew. In the tell-all, the former backup dancer and the father of Spears' sons, Sean, 20, and Jayden, 19, claims she did cocaine while breastfeeding, cheated with a backup dancer and once stood outside the boys' bedroom with a knife in her hand while they slept.

Although Spears' rep blasted the book, claiming Federline is " profiting off her" and "all she cares about are her kids," the scandalous revelations have caused her to spin "out of control," the source said.

An insider added she's been hitting the booze hard recently to numb the pain of her lonely life, but it's ultimately doing her a lot more harm than good.