Paris Speaks Out About Split With Nicole

The rift between Paris Hilton and her Simple Life co-star, Nicole Richie, has escalated into an all-out war.

Hilton has spoken for the first time about the falling out between the pals: “It’s no big secret that Nicole and I are no longer friends,” Hilton said in a statement Wednesday. “Nicole knows what she did, and that’s all I’m ever going to say about it.”

A source close to Paris tells PEOPLE that Richie is jealous of the media attention her blonder costar receives and resents being left out of things like Hilton’s Feb. 5 hosting gig on Saturday Night Live. In fact, says the source, Richie tried to get even for that perceived slight by throwing a party to celebrate the SNL stint and then screening Paris’s infamous 2003 sex video instead.

“Paris was very hurt,” says the source. “She loves Nicole but believes she is owed an apology.” (Reps for Richie deny the incident.)

Meanwhile Richie’s friends tell PEOPLE that tensions arose because Nicole has grown out of her wild ways, quitting drinking and spending more time with her fiancé , Adam Goldstein. “She just wants to be with Adam and get married,” says one.

Either way, Paris hasn’t wasted any time finding a new sidekick: She’s been keeping company with the equally blonde pal Kimberly Stewart, daughter of singer Rod Stewart. And Paris hasn’t been shy about hinting that it may be a preview of things to come. “Kim is hysterical and crazy fun, and I love that about her,” said Hilton, 24, admitting that she has been lobbying to make Stewart her new costar on the next season of The Simple Life.

So is it goodbye Nicole, hello Kimberly? FOX says no decision has been made. In the end the only thing that seems indisputable is that with The Simple Life no longer so simple, both women are moving on. Richie is reportedly shopping a Newlyweds-style series to MTV, while Hilton is promoting her role in the movie House of Wax and waiting to hear if FOX will hire Stewart. And, according to the source close to Hilton, with their onscreen duo a bust, a reconciliation seems unlikely any time soon.

“Nicole sees (the show) as a business that’s separate from the personal,” says the source, “but Paris doesn’t separate the two.”