By Kev Geoghegan
Newsbeat entertainment reporter
Kelly Brook has to wear a 50s-style bikini at the end of the play
Kelly Brook's new play has opened in London's West End.
In Fat Pig, she plays the bitchy ex-girlfriend of a man who starts dating a much bigger girl.
Celebrity guests included boyfriend, rugby player Danny Cipriani and Craig Revel Horwood and Brendan Cole from Strictly Come dancing.
Speaking to Newsbeat, she admitted she was nervous: "My family and friends were there. I invited too many people but it was great fun."
Asked if her boyfriend was a calming influence on her, Kelly said it was the complete opposite.
She said: "No, it's even worse, 'cause you want to do a good job.
"I think he enjoyed it, he seemed to really love it.
"He likes the theatre so it was good that he could come and see me tonight."
The play, written by New York-based playwright Neil LaBute is set in a west-coast US office and sees Tom fall in love with plus-sized Helen, much to the disgust of colleagues Carter and Jeannie.
It calls for the cast to use American accents throughout the hour and a half long play.
Brook's slipped occasionally during some of the quick-fire dialogue but she insisted she was comfortable with it.
Kelly admitted she was nervous before the curtain went up
She said: "It just helps you get into character and you just feel like you're not yourself.
"It's challenging but it's fun."
She looked stunning at the show's after party, dressed in a long white gown and wearing around £750,000 worth of diamonds.
Brook's co-stars were full of praise for her efforts earlier in the evening.
Kevin Bishop of Star Stories fame said: "She was brilliant, I thought nerves might get the better of her like they were getting the better of me but she was awesome."
The climax of the play has Brook stripped down to a 50s-style bikini but she reckons that it's been getting far too much press, even if it is likely to put a few extra bums on seats.
She said: "It's such a tiny part of the play, I don't know why people make such a big fuss about it because it's the very end scene and its no big deal."