Britney Spears abused drugs in 2007 and 2008 and slept in a car park the night she lost custody of her children, according to new court documents.
The new documents have been triggered by Spears' impending deposition in former manager Sam Lufti's appeal in a legal battle with her family.
Lufti is pursuing a cash settlement from the management job where he says Spears promised him 15 per cent of her US$800,000 a month salary.
In 2007, Lufti met Spears at a nightclub while he was working as a "consultant" at her mother's gas station business.
The documents state at the time Spears was "struggling with drug abuse", estranged from her parents and was involved in a divorce and child custody battle when she met him.
Spears offered Lufti a job as her manager which he accepted on the agreement she would stop using drugs.
But she continued to use drugs and Lufti moved to end the professional relationship in mid-September 2007.
In October she lost custody of her sons and "spent the night in a parking lot", before calling Lufti for help.
She moved in with him until early 2008.
Lufti also helped Spears deal with the 30 to 100 paparazzi who were trailing her.
According to the court documents, Lufti set rules for them including not entering private property, not following her into shops, not running red lights to chase them and saving Spears a parking space when they followed her.
If the paparazzi followed the rules, Lufti would send them Spears' itinerary.
"By January 2008, Britney and Sam trusted the paparazzi and treated them as free bodyguards," the documents state.
In January, Spears was hospitalised twice on a 72-hour psychiatric "hold".
Her father James applied for a temporary restraining order preventing Lufti from having contact with her after the family believed he was controlling every aspect of her life.