In an upcoming documentary (yes, we're serious), Britney Spears candidly discusses her loneliness, regrets and erratic behavior in recent years.

"I sit there and I'll look back and I'm like: I'm a smart person. What the hell was I thinking?" the star says in the documentary, For the Record.

In a short video clip from the film below, the 26-year-old superstar alludes to parts of her tumultuous past: her divorce from Kevin Federline, a couple of forced psychiatric hospitalizations and loss of custody of Jayden James and Sean Preston...

"I've been through a lot in the past two or three years, and there's a lot that people don't know. Sometimes I think I get kind of lonely because you don't open the gate up that much, you know I mean? You're guarded. You have to be that way, so I'm kind of stuck in this place and it's like: How do you deal? And you just have to cope, so that's what I do. I just cope with it. Every day."

Deep. The documentary airs on MTV November 30, just before the release of Circus. The music video for "Womanizer" premieres tonight on 20/20!