In an Instagram post today, the former reality star turned fashion designer opened up about how she is coping with the death in the family.
"My heart is in a million pieces. Mikey, I could always count on you to make me laugh. You had such a good heart and you will be forever missed. I'm at a loss for words but I know u are in a better place and finally at peace," she wrote before adding, "I love u so much RIP."
The mother of three also posted a photo of her as a toddler with her brother showing the two smiling together as kids.
Earlier today, Cavallari released a statement after being informed by police that her brother was found.
"We want to thank everyone for their love, support and prayers during this very difficult time," she said in a statement to E! News. "We have just been informed by the authorities my brother's body has been found. This is a very painful time and we are still processing it all. We kindly ask everyone please respect our privacy during our time of grieving."
Meanwhile, a source tells E! News that the brother and sister were "close and would talk" and that, understandably, "Kristin's heart is broken."
The brother of the former The Hills star's 2014 Honda Civic was found abandoned on Nov. 27 on I-70 in Utah, according to a press release shared by the Grand County Sheriff's Office.
Following a search of the immediate area, authorities could not determine his whereabouts.
Today, however, a spokesperson for the Utah Medical Examiner's Office told E! News, "I can confirm that a body was found and transported to the medical examiner's office in Salt Lake City."