Payne, who shot to global fame with the boy band, died after falling from a third-floor hotel room balcony in Buenos Aires on Wednesday, triggering tributes from fans around the world. He was 31.
Cheryl Tweedy, more commonly known by just her first name, was in a relationship with Payne between 2016 and 2018 and she used her statement to urge the media to remember they had a seven-year-old son, Bear, who could read the reports.
"As I try to navigate this earth-shattering event, and work through my own grief at this indescribably painful time. I'd like to kindly remind everyone that we have lost a human being," she said on her Instagram account.
"What is troubling my spirit the most is that one day Bear will have access to the abhorrent reports and media exploitation we have seen in the past two days. It is breaking my heart further that I cannot protect him from that in his future."
It was not clear which reports she was referring to, but she called on people to "give Liam the little dignity he has left in the wake of his death to rest in some peace at last".
Payne's current girlfriend, Kate Cassidy, said on Instagram she had been "at a complete loss" and she would "continue to love you for the rest of my life".
In the central English city of Wolverhampton, Payne's home town, more than 100 people came to mourn him, often singing some of his songs.
'COMPLETELY DEVASTATED'
The tributes to Payne, who found fame as a teenager, have flowed since he was reported dead.
A joint statement was signed by his One Direction band mates Harry Styles, Louis Tomlinson, Zayn Malik and Niall Horan.
"We're completely devastated by the news of Liam's passing. In time, and when everyone is able to, there will be more to say. But for now, we will take some time to grieve and process the loss of our brother, who we loved dearly.
"We will miss him terribly. We love you Liam."
In a separate statement posted on Instagram on Thursday, Styles said Payne's greatest joy was making people happy.
"The years we spent together will forever remain among the most cherished years of my life," Styles said.
Malik also posted on Instagram about the late singer, along with a photo of them dozing off next to each other.
"I lost a brother when you left us and can't explain to you what I'd give just to give you a hug one last time," he wrote.
Along with a picture of Payne embracing him at a gig, Tomlinson wrote he was beyond lucky to have had him in his life.
"I'm really struggling with the idea of saying goodbye."
Music mogul Simon Cowell, who signed One Direction to his label, posted his tribute on Instagram on Friday, saying he was "truly devastated" and "heartbroken".
"And I want you to know how much love and respect I have for you. Every tear I have shed is a memory of you."
Sharon Osbourne, former judge of TV talent show X Factor, where One Direction was formed, said on Instagram the music industry had let Payne down, describing him as "just a kid when you entered one of the toughest industries in the world".
Prosecutors in Buenos Aires said on Thursday an initial search suggested Payne's fall from the hotel balcony came after substance abuse.
Police earlier said they had found the room in "total disorder" in a search after his death, with various things smashed and medications scattered around.
