United Kingdom, Sept. 21 -- Paris Hilton is "completely heartbroken" by Presley Gerber's death.

The 27-year-old model - son of supermodel Cindy Crawford and businessman Rande Gerber - passed away at a rehab facility after a long battle with addiction issues and now Paris, 45, has opened up about their friendship - calling Presley a "beautiful soul" and admitting she will miss him "more than words can say".

In a post on Instagram, she wrote: "I'm completely heartbroken. I still can't believe this is real.

"Presley, you were such a beautiful soul. So sweet, sensitive, kind and genuine. I cared about you so much, and I'm going to miss you more than words can say.

"I'll always cherish the memories' that they made over the years - the laug...