Kim Richards broke her silence on Monty Brinson's death by penning a tribute to her former husband.

The 51-year-old reality star remembered her ex-spouse and close friend as an "amazing person" in an Instagram post on Monday. Brinson died at age 58 on Sunday following a battle with cancer.

"Yesterday I said goodbye to the best friend I've ever had in my life," Richards wrote. "Monty was an amazing person with an amazing soul. We shared over 30 years of love & happiness and brought a beautiful daughter into [the] world."

"I am so grateful for all that we shared," she continued. "I love you Monty, my angel in heaven, and I know that we [will] be together again one day. I will carry you in my heart always my love. Until then, may you rest in peace."

Richards and Brinson were married from 1985 to 1998, and share 29-year-old daughter Brooke Brinson. The reality star is also mom to 25-year-old daughter Whitney, 24-year-old son Chad and 20-year-old daughter Kimberly with previous partners.

"[Kim and Monty] were still very close, right up until the end," a source told E! News. "Everyone's worried about Kim in the same way they're always kind of worried about her. No one wants to see Kim's health take a step backwards because of grief."

Richards has struggled with substance abuse for years, and is presently on probation for her April public intoxication arrest. Her sister, Kyle Richards, was hopeful about the star's continued sobriety in December, saying Richards seemed "confident and strong."

Richards will make occasional appearances on Season 6 of Bravo reality series "The Real Housewives of Beverly Hills," which airs Tuesdays at 9 p.m. ET.