Nicola Payne learned of her brother Liam Payne's death from a news alert on her phone.
The former One Direction singer died on 16 October, having fallen from a third-floor balcony at a hotel in Buenos Aires, Argentina. He was 31.
On Monday, Nicola took to Instagram to share a lengthy tribute written in honour of her younger sibling, and as part of the statement, revealed she discovered he had passed away via a message from a news website.
"I have posted about Liam and his achievements over the years with a proud sister alert and that has stood then, now and always!!! When I saw the news pop up on my phone that you had left us, I went cold," she wrote. "I wanted so much for it to be untrue. I have spent days hoping that it was a mistake and somebody has got it wrong."
Nicola went on to describe how Liam was an "angel" who "lived to make people smile".
She also vowed that she would always be there for the Strip That Down singer's seven-year-old son Bear, whom he shared with ex-partner Cheryl.
"I hope that you finally found some peace up there and that you always continue to look after us all as you have done in life. We will make sure Bear knows about his daddy and how much you loved him. We promise this. See you soon, Liam. Love you," Nicola concluded.
In addition, Liam's other older sister, Ruth Gibbins, shared her own emotional message.
In the post, Ruth recalled how her brother was always able to make her laugh.
"I don't feel this world was good enough or kind enough to you, and quite often over the last few years, you've had to really try hard to overcome all that was being aimed at you. You just wanted to be loved and to make people happy with your music. You never believed you were good enough, I hope you can now see this outpouring of love that you never received in your time," she reflected. "Thank you for changing my life, thank you for the incredible memories, thank you for always being the best brother and friend I'll ever have!"
Liam's father Geoff Payne has travelled to Argentina to repatriate his body. A funeral is expected to take place in the U.K. next month.
