Holly Madison, Hugh Hefner and Crystal HarrisHolly Madison is finally speaking out on ex-boyfriend and Playboy founder Hugh Hefner's proposal to Playboy Playmate Crystal Harris, and she is not happy. She even warns Hefner to reconsider.

In an interview with Life & Style magazine, Madison says, "I'd like to see Hef settle down. I just want it to be with the right person, and I feel like he's making a hasty decision. I'm not sure Crystal is the best thing for him."

Madison, 31, was one of Hefner's three girlfriends who rose to prominence from the E! reality show 'The Girls Next Door.' But Madison was Hefner's "number one" girlfriend for more than six years before they broke up in October 2008 over his refusal to wed. Harris, 24, moved into the Playboy Mansion in January 2009. Hefner proposed to Harris on Christmas Eve last year.

Madison continues, saying, "Crystal hasn't been around very long – she's a mysterious character. No one knows much about her. Plus, she's very young, probably too young to settle down. I've seen a lot of girls try to date Hef, and some have ulterior motives. I don't think it would be a bad idea for him to get to know her a little better. I think it's possible Crystal could break Hef's heart. They could end up divorcing, and she could take half his money."