Duffy has shared her second new song since revealing in February that she retreated from the public eye in the early 2010s after being drugged, held captive and raped by an unidentified person.

River in the Sky is “for the better days to come”, the pop star said in a post accompanying the the track. Set to piano, the 35-year-old Welsh songwriter born Aimee Anne Duffy sings of being “afraid of the dark”, and of a presence who visits her in the night and “covers me so patiently as I learn to deal with the pain”.

In a yearning chorus, she repeats: “Why oh why do we cry, do we cry / Just like a river in the sky.” It follows the release of Something Beautiful, which Duffy shared on Jo Whiley’s radio show in March.

In February, Duffy posted a message on Instagram – since deleted – in which she said: “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 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.”

In April, she published an essay on her website detailing the ordeal. She said she had been drugged in a restaurant on her birthday before being held captive in her own home and taken to a foreign country.

She wrote that she could not remember getting on a plane, and came around in the back of a moving vehicle. She said that the perpetrator put her in a hotel room and raped her. She said she did not know how she had “the strength to endure those days” and claimed the perpetrator made “veiled confessions of wanting to kill me”.

Duffy said she was sharing her experiences because “we are living in a hurting world”.

Rape Crisis praised Duffy for sharing the statement. “Rape is still a very under-discussed, misunderstood and underreported crime, so when someone like Duffy speaks out in such a powerful way it can make other survivors feel a little bit less alone and less ashamed – which is a very common emotion, now matter how unfounded,” said the organisation’s Katie Russell.

Duffy had largely been out of the public eye since the release of her second album, Endlessly, in 2010. She had shot to fame in 2008 with her debut, Rockferry, which was the biggest-selling album in the UK that year and also a hit in the US.