Duffy has said she was "raped, drugged, and held captive".
The 35-year-old singer has been away from the spotlight since the release of her second studio album Endlessly in 2010, and has now revealed the reason for her "disappearance", as she alleges she underwent a harrowing experience in which she was sexually assaulted and kept "captive over some days".
Writing in an Instagram post, she said: "You can only imagine the amount of times I thought about writing this.
"The way I would write it, how I would feel thereafter. Well, not entirely sure why now is the right time, and what it is that feels exciting and liberating for me to talk. I cannot explain it.
"Many of you wonder what happened to me, where did I disappear to and why.
I was raped and drugged and held captive over some days.
"A journalist contacted me, he found a way to reach me and I told him everything this past summer.
"He was kind and it felt so amazing to finally speak. The truth is, and please trust me I am OK and safe now, I was raped and drugged and held captive over some days."
The Mercy singer says she’s been "recovering" for several years, and chose not to return to the spotlight sooner because she didn’t want to "show the world the sadness in [her] eyes".
She added: "Of course I survived. The recovery took time. There’s no light way to say it. But I can tell you in the last decade, the thousands and thousands of days I committed to wanting to feel the sunshine in my heart again, the sun does now shine.
"You wonder why I did not choose to use my voice to express my pain? I did not want to show the world the sadness in my eyes.
"I asked myself, how can I sing from the heart if it is broken? And slowly it unbroke."
Duffy - whose real name is Aimee Anne Duffy - plans to detail her alleged experience in an upcoming interview, but urged her fans to respect the privacy of her and her family.
She concluded her Instagram post: "In the following weeks I will be posting a spoken interview. If you have any questions I would like to answer them, in the spoken interview, if I can.
"I have a sacred love and sincere appreciation for your kindness over the years. You have been friends. I want to thank you for that x Duffy.
"Please respect this is a gentle move for me to make, for myself, and I do not want any intrusion to my family.
"Please support me to make this a positive experience."
Leave us a comment on our Facebook page @EntertainmentDailyFix and let us know what you think of this story.