LeAnn Rimes' team reportedly fears the star could be "going crazy again".
The country songstress is currently embroiled in a very public bitter battle with her husband's ex-partner Brandi Glanville.
The Real Housewives of Beverly Hills star shares boys Mason, nine, and Jake, five, with Eddie Cibrian, who had an affair with LeAnn while married to Brandi.
LeAnn - who married Eddie last year - has been accused by Brandi of having a "severe" eating disorder and endangering her children.
Sources say Brandi is close to taking action over her claims, with an insider telling the New York Daily News that a battle will "prove difficult because Glanville doesn’t want to hurt Cibrian, whom she believes is a 'good father’."
“Everyone that manages LeAnn, everyone who knows her, says she is going crazy again,” the source added. “Brandi is always kept in the dark. All of the Twitter, rehab nonsense Brandi just doesn’t understand. How could she go perform concerts from there? Nothing is clear.”
LeAnn entered rehab over the summer due to “stress and exhaustion," but left after just one week to perform a series of shows in California.
Yesterday Brandi accused LeAnn of being “unstable” and says she fears for her sons’ safety in a bombshell interview with Us Weekly.
"I see this ending badly - I see someone getting hurt. She's not healthy. And until she's healthy, I don't want her around my children by herself," she said.
"She has [a laxative] in every purse. Mason found one on the floor and thought it was a Skittle! They don't keep sugar in the house. He thought he finally found candy! He gets extremely sick, and that freaks me the f**k out."