Yolanda Foster has just been dealt with a tragic loss.

On Instagram earlier this week, the former Real Housewives of Beverly Hills star shared a post with fans, revealing her longtime friend Ellie had died after a battle with ALS.

"Out of suffering have emerged the strongest souls; I love you my beautiful angel @ellieod .......You are my hero, my best friend and a shining light to all battling #ALS #Girlfriends #Blessings #Life," Foster wrote in the caption of the photo below.

A photo posted by YOLANDA (@yolanda.hadid) on Aug 26, 2016 at 7:23pm PDT

Days later, Foster shared another photo with the caption, "R.I.P and fly with the Angels my love @ellieod Thank you for 16 great years and showing me the meaning of true and loyal friendship until your last breath. You are my hero and will live in my heart forever...... #AlsWarrior #MyBestFriend."

For the past several years, Foster has been enduring a health battle of her own. After being diagnosed with Lyme disease in 2012, just months after marrying her now-ex-husband David, Foster lost the ability to read and write and began to undergo as many treatments as possible in an effort to cure herself of the disease.

As her efforts continue, Foster has removed herself from her role on The Real Housewives of Beverly Hills after starring on the Bravo reality series for four seasons. Foster's exit announcement was made on Instagram in June.

For more on Foster's Lyme disease, check out the Watch What Happens Live clip below.