'The Hills' Star Casey Reinhardt Gets Engaged to Sean Brown -- See the Huge Ring!

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The 'Cupcake Wars' winner shared a picture of her massive ring on Instagram.

Congrats are in order for reality star Casey Reinhardt, who got engaged to boyfriend Sean Brown on Wednesday!

"My breath is taken away... I've never felt happier in my entire life!!!" Reinhardt wrote on an Instagram pic of the proposal. "I love you so much @seanmbrown1!!!! How lucky am I to have found my soulmate... I can't wait to spend the rest of my life with you!!!!!!!!!!! Happiest day of my life!! I feel so blessed!!!"

Reinhardt shared details of her happy day exclusively with ET.

"Earlier in the day, he arranged to see my parents and my brother to get their blessing," she said. "I was getting ready to go out to dinner with Sean and when I turned around to walk out of my dressing room, he was on one knee and simply said 'spend the rest of your life with me.' I screamed 'YES!', he put the ring on my finger and I cried tears of joy and completely ruined my make-up. It was such an amazing experience, so perfect and intimate!"

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Reinhardt, whose older brother Doug is also a Hills alum (in addition to being Paris Hilton’s ex-boyfriend), also shared a picture of her massive ring, on an Instagram captioned "My fiancé!!!!! ❤️❤️❤️❤️❤️" Her husband-to-be is the nephew of Nicole Brown Simpson.

"Sean designed the ring with our family jeweler," Reinhardt told ET. "It is a pear-shaped 12 carat [ring] adorned with an additional 3 carats around the center diamond. It is absolutely stunning, he did such an exceptional job!! I couldn’t have dreamt of a more beautiful ring."

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Reinhardt wouldn’t confirm which of her Laguna Beach or Hills co-stars might be invite to the wedding, but told ET that "I plan on inviting all of my favorite people." Casey can take a page from her old friend and co-star Lauren Conrad’s book, as the fashion designer opened up about about the ups and downs of marriage on her blog on Tuesday.

"My favorite thing about being married is knowing that I have a partner in life that I get to do so many wonderful things with. Dreaming of the things we will do 20 years from now is so fun," Conrad wrote, while also acknowledging that compromise is a big part of married life to husband William Tell.

"You always want to be considerate of each other," she confessed. "It's not just about you anymore."

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Reinhardt, who appeared on Laguna Beach and The Hills, also won an episode of Food Network's Cupcake Wars in 2011. She is the owner of Casey's Cupcakes, a boutique bakery with locations in Laguna Beach, Newport Beach, Riverside, and Irvine, California. Reinhardt even created a special "Enchanting Engagement" cupcake to celebrate her upcoming nuptials!

"Toast to a lifetime of love with this Tahitian vanilla cake, with hints of cherry and Maraschino cherry pieces, white chocolate chips, Tahitian vanilla buttercream frosting, haloed with gold sugar crystals, gold glitter and topped with a beautiful sugar diamond," reads the Casey's Cupcakes Facebook page.

Congrats to the happy couple!

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