Pop star Fergie has opened up about the 'holy war' raging inside her mind during her most difficult days and how she eventually found freedom in a church.

The 'Black Eyed Peas' star went into surprising detail about the disturbing visions she was having of 'little devils' in an extended version of her new release, 'A Little Work'. 

She recounted some of the difficult periods she went through when 'devils' were appearing to her constantly and she was emotionally pushed to the brink.

'I got to a point where I was seeing devils everywhere,' she says. 'Devil faces. Creatures that would appear to me would say "fly, fly fly." Maybe not even saying it, just flying around.

'I would constantly be in this state of listening to the messages that all of these creatures... what they were going to tell me. What I should do. And life became almost like this whole game.

'I was just going to lose it I was just going to start screaming at everybody in the street.'

Fergie relayed her dark experience in a voice over as shots of her face appeared in black and white alongside music video clips in her new track promo.

As she went on, the pop star, who recently announced her split from husband Josh Duhamel, described the 'real fear' she felt during her internal struggle and how apart she felt from reality.

'I was living in an alternate parallel universe to what was really going on in this world,' she said. 'They're all going to get me, the swat team... everything. This was a real fear, serious fear.'

The turning point for the 'Big Girls Don't Cry' singer came when she walked into an empty church and experienced what she describes as an 'epiphany.'

'It was just this epiphany I had in this holy war. The war between good and evil, that good will always be a little more powerful,' she shared.

Fergie is a regular at church and often takes her three-year-old son Axl.

The 42-year-old has previously spoken about her struggle with an 'alternate reality' and the conversation she had with God in an interview with Oprah Winfrey.

She told the talk show host how she made a promise to God inside the church to stop doing drugs and her life changed from that time on. You can read more of her remarkable account here: Fergie spotted attending church in recent weeks