Britney Spears has blamed her ex-husband Kevin Federline's failed rap career for the couple's break-up.

The pop star claims her romance with Federline was over long before she filed for divorce - because he was too busy building his own career to spend time with her.

She says, "He started to do an album for himself and he started to do things for himself, and I just never saw him anymore."

But she was still devastated when she realised the marriage was over: "When it ended I felt so alone. I didn't really wanna think about the reality of it. I never faced it?I just ran."

The break-up brought back painful memories of her split from Justin Timberlake.

Spears adds, "He was a part of the magnitude of what I had become. So when he was gone I was like, 'What am I supposed to do with myself?' I was devastated."