Speaking to iNews, the "Milf$" singer said: "At my lowest point, I was [suffering from] chemically induced psychosis and dementia".
Fergie's hallucinations were extreme: On certain occasions, she told iNews, she believed government agencies including the CIA and Federal Bureau of Investigation were pursuing her. Only a year later after I stopped taking illegal drugs, the hallucinations stopped, and my brain was normal again to think.
And when she ran outside, she saw firsthand how drastically the drugs had affected her, seeing no SWAT, CIA or Federal Bureau of Investigation teams in the church parking lot.
"They tried to kick me out, because I was moving down the aisles in this insane way, as I thought there was an infrared camera in the church trying to check for my body", Fergie said.
Fergie also talked about what she says was her lowest point, and how hitting rock bottom helped her realize she needed help and it was time to make a change.
"The drug was my boyfriend, with whom I was extremely hard to leave", admitted 42-year-old singer.
The singer/dancer recently opened up about her life prior to fame and fortune, a life most couldn't conjure up in their worst nightmare.
Fergie didn't spare the details in discussing her drug-filled past in an iNews interview posted on Thursday. It was a freeing moment'. Because that's my strength, my faith, my hope for something better, ' she added.
"I thank the day it happened to me", she admitted. I bolted past the altar into a hallway, and two people were chasing me, ' she recalled.
In September, the singer and her husband, actor Josh Duhamel, announced they were splitting up after eight years of marriage.
Fergie doesn't want to erase her past.
The 42-year-old mum released her second solo studio album, Double Duchess, earlier this year.
Proving that she is just like any other working mother who feels guilt while spending time apart from her son, Fergie is grateful for modern technology to keep them connected.
She told Extra: "You never know what the universe is going to throw at you".