Gwen Stefani felt like her "life blew up" as her marriage to Gavin Rossdale collapsed.
The 46-year-old star announced the end of their 13-year marriage in August, but Gwen has revealed the "unexpected" split had occurred well before then.
Gwen said: "Everybody knows that my life blew up last February. I'd just been dealing with that. Unexpected. I was going along thinking that was going to be the rest of my life and it's not. I don't know what happened."
The singer, who is currently dating Blake Shelton, also revealed the dramatic split was the inspiration behind her new hit single Used to Love You.
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She told KIIS FM: "There was one night, the epicenter of the whole thing - that's the most I can say about that - and the next day I wrote the chorus to Used to Love You.
"But I didn't know it was Used to Love You. I just had written all this stuff and it had happened to be in there buried in a bunch of lyrics that I had written."
Gwen - who shares sons Kingston, nine, Zuma, seven, and Apollo, 20 months, with her ex-husband - admitted making music during this turbulent period in her life proved to be cathartic.
She said: "I just knew that I needed to write. Even the first day that I went into the studio, I didn't want to get out of bed.
"You know when you're so down that you just don't want to do anything? I went to the studio and I wrote a song. And it wasn't just writing a song to a track or something.
"It was like sitting at a piano with a guy I didn't know and an engineer that's sitting there who I didn't know, and all this stuff is going down they didn't know."
- Bang! Showbiz