Socialite Paris Hilton sympathises with her friend Brooke Mueller, estranged wife of Charlie Sheen, who is struggling to overcome substance abuse problems.
Mueller was filming for Hilton's new reality show "The World According to Paris" at the time and the hotel heiress admits it was difficult to watch her friend suffer.
"You know, it was a lot of things going on during that whole Charlie thing during the show and I think she was going through a lot," Hilton said on " The Tonight Show" with Jay Leno.
Mueller has turned to professionals to help her.
"Right now she's in treatment and I'm wishing her the best. She's going through a lot. It has (been hard to see). It's definitely been something that she has been struggling with since her teen years and it's a daily struggle,"