Sarah Ferguson is mourningthe death of Lisa Marie Presley.

She was rushed to the hospital where she was placed on life support and into a medically induced coma.

The Duchess of York has been friends with Presley for well over a decade.

Sarah Ferguson choker

Ferguson and Presley have been through a lot together, as evidenced by Ferguson’s heartfeltInstagramcaption.

Through the years, the two women were there for one another during the highs and lows.

I am deeply saddened my sissy, you are in my heart," the duchess wrote.

Lisa Marie Presley and Sarah Ferguson

According toTMZ, Keough died by suicide, leaving his mother absolutely gutted.

She adored that boy.

He was the love of her life," Lisa Marie Presley’s manager told TMZ at the time.

Ferguson also felt that pain and grieved alongside her dear friend.

“You stayed with me in my darkest moment & I am here in Yours.

Love you my sister Lisa Marie … wherever, whatever I am with you, in all steadfastness.

Dearest Lisa Marie, Finley, Harper and Riley.

You have a family here.

Lisa Marie Presley is survived by her three daughters: Riley Keough, Finley Lockwood, and Harper Lockwood.