Simon Cowell, the mastermind behind the formation of One Direction, paid tribute to Liam Payne after his sudden death Oct. 16.

"You never really know how you feel about someone until a moment like this happens," Cowell wrote on Instagram. "Liam, I am truly devastated. Heartbroken. And I feel empty. 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.

"This is so difficult to put in words right now. I went outside today, and I thought about so many times we had together. I wanted to let you know what I would always say to the thousands of people who would always ask me. What is Liam like? And I would tell them you were kind, funny, sweet, thoughtful, humble, focused. And how much you loved music. And how much love you genuinely had for the fans."

LIAM PAYNE'S ONE DIRECTION BANDMATE SHARES ‘HEARTBREAKING’ FINAL MOMENTS TOGETHER IN ARGENTINA

Simon Cowell with the members of One Direction

Simon Cowell helped create One Direction after the boys auditioned on "The X Factor." (Getty Images)

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Payne died Oct. 16 after falling from a hotel balcony in Buenos Aires.

Payne was 14 when he first auditioned for "The X Factor" in 2008. He returned to audition two years later and was chosen by Cowell to join a super group. The TV judge matched Payne up with Niall Horan, Harry Styles, Zayn Malik and Louis Tomlinson.

They formed the boy band One Direction and became one of the bestselling groups of all time.

"I had to tell you when you were 14 that this wasn't your time," Cowell added. "And we both made a promise that we would meet again. A lot of people would have given up. You didn't. You came back and within months the whole world knew Liam. And you never forgot the fans. I watched you spending so much time with people who had wanted to meet you. You really cared.

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Liam Payne attends a world premiere

Liam Payne's preliminary cause of death was revealed by Argentinian authorities. (Getty Images)

"You came to see me last year. Not for a meeting. Just to sit and talk. And we reminisced about all of the fun times we had together. And how proud you were to be a dad. After you left, I was reminded that you were still the sweet, kind boy I met all those years ago. I have met your son, Bear. He has your smile and that twinkle in his eyes you have. And he will be so proud of everything you achieved. And how you achieved it.

"I always thought of the 5 of you in the band as brothers," he added. "And reading their messages today I believe you were. And now Liam, I can see the effect you had on so many people. Because you left us too soon. Rest in peace my friend. And I am sending my love, thoughts and prayers to your family."

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Members of One Direction perform in 2012

One Direction performs in 2012. (Getty Images)

One Direction is known for the hits "What Makes You Beautiful," "Night Changes," "Story of My Life" and "Steal My Girl."

In five years, One Direction released five chart-topping studio albums and embarked on four world tours.

By 2016, One Direction announced an indefinite hiatus to pursue solo projects.

The members of One Direction in 2011

Zayn Malik, Louis Tomlinson, Harry Styles, Liam Payne and Niall Horan formed One Direction in 2010. The group took an indefinite hiatus in 2016. (Getty Images)

The group "will miss him terribly."

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"We’re completely devastated by the news of Liam’s passing," a statement released by the band on social media said. "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. The memories we shared with him will be treasured forever. For now, our thoughts are with his family, his friends, and the fans who loved him alongside us. We will miss him terribly. We love you Liam."