Kristin Cavallari on brother's death: "My heart is in a million pieces"

Kristin Cavallari shared a heartbreaking Instagram photo Thursday in the wake of the brother's death.

The touching post comes shortly after Michael Cavallari was found dead at age 30. Authorities discovered his body in Utah after his 2014 Honda Civic was found abandoned on Nov. 27 on I-70.

"My heart is in a million pieces," Kristin, 28, wrote on Instagram alongside a photo of them when they were kids. "Mikey, I could always count on you to make me laugh. You had such a good heart and will be forever missed. I'm at a loss for words but I know u are in a better place and finally at peace. I love u so much RIP."

"We want to thank everyone for their love, support and prayers during this very difficult time," Kristin told CBS News Thursday. "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."

Michael was recently arrested in Orange County, California, for criminal threats on allegations that he acted threateningly toward a woman. He was released from jail on Nov. 25 and went missing two days later. A rancher found his 2014 Honda Civic in Utah.

On Thursday, the Grand County, Utah Sheriff's Office released the following statement: "At approximately 10:30 a.m. search crews located remains believed to be that of Michael Cavallari. At this time, the body is being transported to the Office of the Utah Medical Examiner for positive identification and to determine the cause of death. The search crews were searching the Salt Wash area, near exit 175 on I-70 in Grand County. The terrain where the body was located is a steep and very rocky area."

Michael, whose brother-in-law is Chicago Bears quarterback Jay Cutler, was single and had no children.

Kristin and Cutler, who are parents to two boys, welcomed a baby girl last month.