The Backstreet Boy and Hilton dated for eight months before splitting in July 2004--the same month Murray announced his engagement to his One Tree Hill costar Sophia Bush after proposing in between filming scenes of the horror movie in Australia.
Carter admits he was unfaithful to Hilton--but only after he was told by mutual friends of the couple that the hotel heiress was seeing other men behind his back.
He tells gossip site PageSix.com, "I'd fallen head-over-heels with this chick. Then, all of a sudden, three months go by and I got people telling me, 'Nick, you know what Paris is doing to you,' and I got a little upset.
"So then I just decided to fight back a little bit and started doing my own thing again. The result is I hooked up with Ashlee Simpson. When Paris came back from Australia, they talked to each other and she found out about it.
"So I brought it up to her and said, 'You know what I did, and now it's your turn. Why don't you tell me what you did?' And she goes, 'I never did anything! I never cheated on you.'
"I had kind of started to really like Ashlee and I was thinking about the dating stage. Then, before you know it, f**king b**ch-face comes back.
"I got so burnt over that whole Paris s**t with all this swinging and switching. Whatever happened to morals and values?"
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