The Australian singer and television personality, who recently relaunched her music career, said that she struggled to leave the house during her one-year marriage to high school sweetheart Jamie Babbington.
Coulter told The Sunday Mail: "I was living my dream but behind closed doors my personal life was a mess. I felt alone, I bottled it all up and it made things worse. I wouldn't leave the house for days at a time. I'd sit in the house all day and do nothing. There was this big black cloud hanging over me all the time and I didn't know how to get away from it."
The 26-year-old has signed on to join Marie Claire magazine's 'Shine a Light' mental health awareness campaign along with stars such as Asher Keddie, Zoe Tuckwell-Smith and Ada Nicodemou.
She said: "It's something I've been through and something I have experienced so if I can use my voice to shed some light and help other people feel confident and comfortable enough to know they are not alone, then that's great."
Coulter recently shed 25kg with the help of her personal trainer boyfriend Rich Harrison and said that she "couldn't be happier" now, adding: "Things don't weigh me down anymore. I confront things and I move on. I don't dwell on things, I don't let things simmer under the surface. I am where it starts and where it ends. I have the power in my life to be happy."
> Ricki-Lee Coulter: 'Losing weight wasn't easy'
> Ricki-Lee Coulter shows off new body in raunchy photoshoot
Watch Ricki-Lee Coulter perform 'Raining Diamonds' on The X Factor Australia below: