"The Real Housewives of Beverly Hills" star Kim Richards paid a touching tribute to Monty Brinson by posting a photo of herself and her late ex-husband on Instagram, referring to him as the "best friend I've ever had in my life."

A photo posted by Kim Richards (@kimrichards11) on Jan 25, 2016 at 5:21pm PST

"Monty was an amazing person with an amazing soul. We shared over 30 years of love & happiness and brought a beautiful daughter into world," she wrote.

"I am so grateful for all that we shared. I know we will be together again one day. I love you Monty, my angel in heaven, and I know that we be together again one day. I will carry you in my heart always my love."

Brinson passed away on Sunday, Jan. 24, at the age of 58 after a long battle with cancer.

He and Richards were married from 1985 to 1988. Both welcomed Brooke, their only child together, who is now 29-years-old, a year after they got married. They remained close friends after they divorced, HNGN previously reported.

Rick Hilton, Brinson's former brother-in-law, who's married to Richards' half-sister Kathy, announced his death on Instagram Sunday night.

"We have lost Monty Brinson after a brave battle with cancer," he wrote. "His heart was a big as the moon and he was loved by all he met. He will be sorely missed. I love you always!"