Playboy founder Hugh Hefner is getting ready for his wedding to Crystal Harris in June, but he says there's one lady in his life who won't be attending: Holly Madison.

"I think Holly [Madison] has expressed publicly that it would be a little strange if she was there and I respect that," Hefner told PEOPLE while celebrating his 85th birthday in Las Vegas.

Madison and Hefner were together for over six years and the 'Holly's World' star hoped to one day marry the Playboy mogul. However, the pair has since split and now Hefner is set to walk down the aisle with 24-year-old Harris at a June 18 wedding.

Rumors have been swirling that Harris has insisted against inviting Hefner's ex-girlfriends to the wedding, including Kendra Wilkinson and Bridget Marquardt. Wilkinson has even vented to the press about not receiving an invitation to Hef's big day. However, Hefner says any claim about Wilkinson not being invited is nonsense.