The 41-year-old singer’s partner filed for divorce from her this week and friends have now told how she apparently hurled blades in the house she shared with the personal trainer-turned actor.

BRITNEY Spears’ estranged husband Sam Asghari is said to have ended their marriage after her behaviour grew so disturbingly “erratic” she allegedly chucked knives at the walls of her mansion.

The 41-year-old ‘Toxic’ singer’s partner filed for divorce from her on Wednesday and friends have now told how she apparently hurled blades in the house she shared with the personal trainer-turned actor.

One source told The Sun: “Her behaviour has become concerning and everyone is worried about her.

“She has been acting increasingly erratic and is in a vulnerable state.

“Sam was bearing the brunt and it proved too much. It’s all plunged to a new low and is sad to see.”

Another insider told the publication: “She’s very volatile, always ranting and shouting at the staff over minor things and making ridiculous demands.

“There’s smashed glass all over the house because Britney will just throw things.

“She has a weird obsession with knives. She has been throwing them at the walls and hiding them down the sofa.

“It is as though she is paranoid someone is after her and she needs the knives as protection.”

Another source told US showbiz website TMZ there were knives all over the house, including in the couple’s bedroom.

They added: “Britney tended to fly off the handle at the smallest slight and that terrified Sam.”

Spears’s sister Jamie-Lynn Spears, 32, said in her autobiography in January that Spears could be “paranoid and erratic”.

Spears’s friends – including Madonna, 65, Paris Hilton, 42, and 31-year-old Selena Gomez – have all stood by the singer by unfollowing Asghari on social media.

Singer Pink, 43, also changed the lyrics to her 2001 single ‘Don’t Let Me Get Me’ to brand Britney “sweet” during a performance in Detroit.

Court documents filed on Thursday have revealed Asghari was asking Spears for spousal support and to cover his lawyer’s fees, but he has denied via his representative he would be challenging a pre-nuptial agreement he and Spears signed ahead of their wedding 14 months ago.