Grammy award-winning singer Duffy has revealed she was drugged and raped after being held captive by an attacker.
The 35-year-old Welsh star posted on her verified Instagram account that her "recovery took time".
The performer, who had a UK number one single Mercy in 2008, wrote to her 33,000 followers: "The truth is, and please trust me I am OK and safe now."
"I was raped and drugged and held captive over some days," she wrote.
Duffy, whose debut album Rockferry went seven times platinum as it went to number one in six countries, won three Brit Awards and a Grammy following her breakthrough.
At the Brits, she won British Breakthrough, Best British Female and Best British Album awards.
"You can only imagine the amount of times I thought about writing this," she wrote on Instagram.
"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. 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. 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."
'Sadness in my eyes'
Duffy - whose real name is Aimee Anne Duffy - went to number one in 12 countries with Mercy, which was the UK's third-best-selling single of 2008 with sales of more than 500,000 copies.
The singer, from Nefyn in Gwynedd, then enjoyed success with her first album Rockferry as it became the UK's biggest selling album of 2008.
"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," she added.
"I asked myself, how can I sing from the heart if it is broken?
"And slowly it unbroke. 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."
Eleri Butler, chief executive of Welsh Women's Aid, told BBC Radio Wales Breakfast with Claire Summers the singer's choice to speak out was a "strong, courageous and powerful statement".
"It's really difficult to speak out… for some women it's the right time to talk many years after the experience, and for some it's never the right time," she said.
The BBC attempted to contact Duffy to confirm the details of her post.