Matthews admitted to having suffered a breakdown last year after becoming "worn out" by the band being catapulted into the public eye.
The problem led to an extended silence for the band, which had quickly risen to stardom with hits including Road Rage and Mulder and Scully.
Last month, the Welsh diva told BBC's Five Live that she had grown to dislike the sound of her own singing voice, but denied she had been depressed.
Matthews admitted to having suffered a breakdown last year after becoming "worn out" by the band being catapulted into the public eye.
But in an interview with Q magazine this month, Matthews conceded she might well have depressed at one stage.
She also explained that her fear of commitment had resulted in her breaking off her engagement a month later.
The article went on to reveal that rows within the band had resulted in Matthews having doubts about herself as an artist and Catatonia scrapped a tour in 1999 as a result of the internal problems.
The singer said the "turning point" happened at an arena concert when the band began a song and she could not remember the words. "The fear set in," she said.
"I've never in my whole life doubted me, doubted my part in this band, until that point. But when I thought of going on stage in front of our fans it was like going into an exam when you know you've done no revision."
Matthews said she dealt with it by leaving the UK and staying with friends in Los Angeles for a month.
"Maybe it was depression," she said. "I haven't been to see anyone. I'm
spooked out by counsellors - anyone who looks too long in your eyes and tells
you things about yourself."
Matthews, a former trainee psychiatric nurse, said she had planned to marry boyfriend Anthony Genn.
The couple split only about 50 days after they became engaged.
"Commitment - scared me absolutely to death, that little ring of metal. And it was mutual," she said.
The star said she had worked and played hard and added she had been grateful to the other band members for being patient with her.