Liam Payne’s sister has shared an emotional tribute to the late One Direction star.

In a post on Instagram, Ruth Gibbins wrote that she doesn’t “believe this is happening” after the singer died in Argentina on Wednesday following a fall from a hotel balcony. He was 31. Payne had two sisters, Nicola and Ruth.

Gibbins shared that she used to keep notes on her phone reminding her of things she wanted to tell Payne and said it’s “only right I tell him now,” addressing the second half of her message to her brother.

“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,” she wrote.“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.”After promising that Payne’s 7-year-old son Bear will “always know how incredible his Dad is,” Gibbins added, “I’m sorry I couldn’t save you.”

Payne’s sibling described her brother as her “best friend” and recalled how she was inspired to get her driver’s license in order to see him after he moved out at age 17 to pursue a singing career. She noted she would “regularly drive to have tea with him” and “used to love picking him up from work when it all started.”Payne “knew he could call me anytime, any day and I would pick up or that I would always fetch him if he needed to just come home,” she reflected. “Our calls would often result in me laughing at his ideas and next adventure, talking through his plans and working through his issues but it would always end with ‘love you miss you’ ‘love you ru.’ “

“Liam, my brain is struggling to catch up with what’s happening and I don’t understand where you’ve gone,” she wrote. “I just want to drive to your house and walk in to music blasting and find you sat there writing a song or walk in to your art phases and sit with you whilst you draw or craft.”She said she was in “awe” of Payne’s talent and kindness and is “proud” to call him “my brother and my best friend.” Gibbins closed the tribute by writing, again addressing Payne, “One last time I need you to know, I’m here if you need anything, I’d drive to the end of the universe to bring you back.”Police previously said that Payne was found dead after they were called to the hotel following reports of an “aggressive man who could be under the effects of drugs and alcohol.”

Tributes to Payne have been pouring in following his death on Wednesday, with the singer’s former One Direction bandmates Harry Styles, Zayn Malik, Niall Horan and Louis Tomlinson honoring him in a joint statement.”We’re completely devastated by the news of Liam’s passing,” they wrote. “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.”

In his own tribute, Styles said he was “truly devastated” by Payne’s death and that the singer’s “greatest joy was making other people happy, and it was an honour to be alongside him as he did it.” Malik postponed the U.S. leg of his tour following the “heartbreaking loss.”

Simon Cowell remembered his former protégé

as “kind, funny, sweet, thoughtful, talented, humble, focused.”

Payne’s girlfriend, Kate Cassidy, said in an Instagram Story that she has been “at a complete loss” since his death. “Nothing about the past few days have felt real,” she wrote. “I ask and pray that you’ll give me the grace and space to navigate this in private.”