Liam Payne’s girlfriend Kate Cassidy has penned an emotional letter in the wake of the singer’s tragic death.

The former One Direction member died on 16 October at the age of 31 after falling from a third-floor balcony at the CasaSur hotel in Buenos Aires, Argentina.

He was visiting the South American country with his girlfriend, American influencer Kate Cassidy, with the pair attending former bandmate Niall Horan’s concert in the weeks before his death.

Cassidy, who left Buenos Aires to return to her home in Florida just two days before Payne’s death, has now penned a heartfelt letter to him on Instagram after issuing a brief statement to fans.

Kate Cassidy has shared a heartbreaking tribute to the late Liam Payne (DANIEL LEAL/AFP via Getty Images)

She wrote: “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.

“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.”

The statement continued: “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 l’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.

“A few weeks ago, we sat outside on a beautiful evening manifesting our lives together. I keep your note close, even though you told me not to look at it. It said, ‘Me and Kate to marry within a year/engaged & together forever 444.’ Liam, I know we’ll be together forever, but not in the way we had planned. You’ll always be with me. I’ve gained a guardian angel.

“I will love you for the rest of my life and beyond, carrying our dreams and memories with me everywhere I go.”

Cassidy concluded the heartbreaking statement with 444; a series of numbers explained in another image in the carousel.

Liam Payne tragically died last week (Gareth Cattermole/Getty Images)

The image explained: “Sequence number 444 is the favorite number sequence of the angels. More often, you will see the number 444 when you are feeling alone. In simple sense, the number 444 reminds you that your angels are always there to support you.

“When you see this number you will be assured that you are protected and loved by the angels.”

Police and local officials are still looking into Payne’s death, with those in Argentina confirming on Tuesday (22 October) that toxicology reports are still incomplete.

That also means the 31-year-old’s body cannot be returned to his family in the UK until the reports are done.