By ELLEN GOODSTEIN
Britney Spears walked out on party-loving hubby Kevin Federline the morning after sources say she sent her bodyguard to a nightclub to make sure he was being faithful.
Insiders told The National Enquirer that the 23-year-old pop princess — still battling the baby blues — ran home to her mom in Louisiana with six-week-old Sean on October 20.
There, the source says, she cried her eyes out over a deepening crisis in her marriage to Kevin, 27.
Despite the distance between them, the couple are then said to have had another blow-up.
Over the phone, Kevin allegedly told his wife he was too busy working on his new music to collect her and their son from the airport when she was ready to return some six days later.
The couple eventually came to an uneasy truce and Britney and the baby returned to California after a week away. But now, say sources, the arguing has put a terrible strain on the marriage — and they could be heading for a more permanent split. Britney is said to fear Kevin is reverting to the behavior that led him to leave his girlfriend Shar Jackson when she was pregnant with their second child.
"Kevin was doing everything right when Britney was still recovering from her C-section surgery," said a close source.
"But now that Britney's up and around again, Kevin's ready to party, hit the clubs, work on his music career and leave Britney to care for Sean all by herself.
"Britney is a devoted new mom and wants to spend all her time with the baby. But Kevin is just not interested in staying home all the time and it's caused problems for the couple. Kevin has been going out at night leaving Britney alone with Sean. She wants to lean on him but he's not always there for her."
Britney has been miserable and angry and crying a lot, said the source, adding: "They have been arguing constantly about it."
The breaking point came on the night of October 19 " when Kevin left Britney and the baby to go out to the trendy Mood nightspot in L.A.