Britney Spears opens up about her breakdown for the first time

Britney Spears has spoken for the first time about her highly-publicised public meltdown.

In an upcoming documentary designed to help launch her comeback, the singer candidly addresses her erratic behaviour and her ongoing battle with loneliness.

Opening up: Britney Spears in her upcoming documentary For The Record

'I sit there and I look back and I'm like, "I'm a smart person. What the hell was I thinking?"' Spears said in an interview to air on MTV on Nov. 30, two days before the release of her new album.

'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?' she continues.

'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 cope, and that's what I do. I just cope with it, every day.'

The 90-minute special, Britney: For The Record, was executive-produced by Spears' manager Larry Rudolph.

It features behind-the-scenes footage of the singer and her talking about her life over the past two years.

And she sure has got a lot to talk about.

Britney and Kevin Federline's three-year marriage ended in a divorce, and she went on to lose custody over sons Sean Preston, three, and two-year-old Jayden James.

Sweet treat: Britney ventured out for ice cream with friends in LA yesterday

Comeback trail: Britney is gearing up to release her new album Circus in December

February last year marked a period of strange behavior by Spears, during which she shaved her head, got two new tattoos and hit the L.A. club scene.

Shortly before she checking into a rehab facility, she attacked a paparazzo's car with a green umbrella.

She then endured another setback after a disastrous performance at the 2007 MTV Video Music Awards where she delivered a shambolic performance of Gimme More which was panned by fans and critics.

Then in January this year, she was put under lockdown at a mental institution after she held her son hostage at her L.A. home and refused to hand him over to Federline.

She has since healed a long-standing rift with her mother Lynne Spears and reinstated her former manager Larry Ruldolph.

Now on the comeback trail, Spears is releasing her sixth album, Circus, on Dec. 2, her 27th birthday.

The first single Womanizer debuted this week at No. 26 in the mainstream US charts and is already an iTunes top-selling track.

Spears says she's hoping this TV special will 'set the record straight' about her life.