Audrina Patridge is mourning the loss of her niece, Sadie, who died one week after her 15th birthday.
“My heart hurts to even write this. My beautiful niece is now in heaven,” the Hills alum, 37, wrote via Instagram on Tuesday, February 14, alongside a slideshow of sweet photos with her late niece. “I know Its not goodbye forever, but it is the hardest to say goodbye for now. We will miss you and cherish every single moment we had with you. Rest in peace Say Say!! We love you forever & ever!”
The reality star’s heartbreaking post was immediately met with heartfelt condolences, including several of her former Hills costars.
“Omgggg this kills me,” Kristin Cavallari wrote. “So so sorry for your loss Audrina. This is heartbreaking,” replied Brody Jenner. “Sending love to you and the family.”
“Audrina! I’m so so sorry! 
sending all the love and light to you and your family,” penned Rachel Bilson. “I’m so sorry Audrina. So so tragic,” shared Real Housewives of Orange County alum Meghan King. “Sending prayers for peace and strength.”
Casey Loza — Sadie’s mom and Audrina’s sister — shared the devastating news via social media earlier that day.
“Sadie Raine Loza has left this Earth for the heavens,” Loza captioned a selfie of her daughter. “Writing this was the hardest thing I ever have had to do, not knowing the right words I’ll leave you with this, Sadie liked to remind me that the first law of thermodynamics aka (Law of Conservation of Energy) works in all spheres of life. ‘Energy cannot be created or destroyed, it can only be changed from one form to another.’”
Loza continued: “Transformation is a better word than death. Her story will save countless lives, her memory will never be forgotten. Rest In Peace you brilliant starseed. You’re with your creator. We will miss you dearly. I love you.”
Sadie’s untimely death comes just one week after her 15th birthday.
“I cant believe youre 15. it feels like the years flew by and we still have so many more adventures to go on!” Loza wrote via Instagram on Sunday, February 5, underneath a video of the teen holding a cake with lit candles as her family sang “Happy Birthday.”
“Aliens in sedona, portals, learning to drive in the desert hahah i love you so much my little clone. youre so beautiful, kind, smart and funny!! That dryyy af british humor tho,” Patridge’s sister continued in her birthday tribute to her daughter. “Im so proud to be your mom and i cannot wait to see the insane ancient civilization architecture you’re going to construct someday. i love you so so much my sadie raine. .”
In addition to Casey, Audrina has another sister, Samantha Patridge, as well as a brother, Mark Patridge. The reality star is mom of 6-year-old daughter Kirra, whom she shares with ex-husband Corey Bohan.