Singer Gwen Stefani says her and estranged husband Gavin Rossdale’s marriage was on the rocks before the birth of their 20-month-old son, Apollo, and she went through "hard times" last year.

The ‘Used to Love You’ hitmaker, who filed for divorce from the Bush frontman in August after 13 years of marriage, admits she went through "hard times before the baby, personally" last year and credits her role as a mentor on ‘The Voice’ USA for giving her a new lease of life, reports

The 46-year-old star, who also has sons Kingston, nine, and Zuma, seven, with her estranged husband, said: "I got so much out of that first season that I didn’t expect, creatively, from being around so much music. There were hard times before the baby, personally, that were just not good. And then having Apollo, and being on the show, and being refreshed — it was just like, Whoa!"

"Filming the show…was so amazing. I cried every day I was there. It was so intense. But I’m in a really positive place now,” Stefani added.

The singer, who recently started dating her fellow mentor Blake Shelton, walked down the aisle with Gavin, 50, in 2002 in a pink ombré Christian Dior gown but recently began clearing out her closet.