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The night before her 34th birthday, Kate Hudson told Us Weekly she had only one wish. "I just want to hang with my family," the "Reluctant Fundamentalist" actress said at the Tiffany & Co. Blue Book Ball on Apr. 18.

Imagine Hudson's reaction two days later when her fiance, Matthew Bellamy, organized a secret bash in his bride-to-be's honor! "Kate was totally surprised," a source tells Us of the soiree, held at a friend's place in New York City's West Village neighborhood. "The party started outside, but it was freezing so people moved inside and danced."

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Famous attendees included Cameron Diaz, Judd Apatow and Leslie Mann (who met up with Reese Witherspoon at Manhattan's Greenwich Hotel just days after her Apr. 19 arrest). "Kate loves to dance, and she was just really happy talking to everyone," a source reveals. "She looked beautiful and beaming in a tight metallic dress."

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Hudson spent her actual birthday, Apr. 19, watching Bellamy's band Muse perform at the IZOD Center in East Rutherford, N.J. "They're very supportive of each other's careers," an insider says of the engaged couple. "They're so happy together."

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The Oscar-nominated actress and mom to sons Ryder, 9, and Bingham, 21 months, got engaged to the British rocker, 34, in the spring of 2011.

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