She started her Instagram message: “I don’t even know where to begin. My heart is shattered in ways I can’t put into words.
“I wish you could see the huge impact you’ve had on the world, even as it feels so dark right now. You brought so much happiness and positivity to everyone – millions of fans, your family, friends, and especially me. You are so incredibly loved.
“You are – because I can’t say were – my best friend, the love of my life, and everyone you touched felt just as special as I did. Your energy was contagious, lighting up every room you walked into.”
She continued: “None of this feels real, and I can’t wrap my head around this new reality of not having you here. I’m struggling to figure out how to live in a world without you by my side. Together, we got to be kids again, always finding joy in the smallest things.
“Liam, you had the kindest soul and the most fun-loving spirit. It feels like I’ve lost the best part of myself. I can’t imagine a day without your laughter and love. You brought so much light into my life.”
Payne’s sudden death led to an outpouring of grief from his family, friends and fans around the world.
His father Geoff is now in the Argentine capital Buenos Aires, and authorities are carrying out tests before allowing his body to be returned to the UK.
They are also reviewing phone, computer and security camera evidence to establish the full circumstances of his death.