Big Brother stars Cody Nickson and Jessica Graf‘s relationship was always more than a showmance — and on Sunday, they made things official, tying the knot in an intimate black-tie affair.

“Our wildest dreams came true today — we’re married!” the reality stars — who are also expecting their first child together — tell PEOPLE exclusively. “Being surrounded by our closest family and friends and sharing this special day with them was all we ever wanted. We are so lucky to have found each other in the most unconventional of ways but we did. We found our forever in each other and can’t wait to begin this new chapter of our lives.”

Get push notifications with news, features and more.

Nickson, 33, and Graf, 27, exchanged wedding bands by Joey from Hamra Diamonds and vows they wrote themselves in front of less than 100 guests (including Big Brother alums Mark Jansen and Elena Davies, and Amazing Race costar Conor Daly) during an outdoor ceremony at The Chateau Le Dome at Saddlerock Ranch in Malibu.

“Fall in L.A. is just so gorgeous out, so I wanted to be dancing under the stars all night long,” Graf says. “I wanted for it to be dripping in flowers, and string lights and lots and lots of candles. I wanted it to look just very romantic. Like a daydream.”

As a special touch, two seats were left empty for the loved ones the couple had lost: his brother Dylan and her late father.

The groom wore cowboy boots with his tux, while the bride donned a silk gown with a dramatic train designed by Mark Zunino, carrying a bouquet of black orchids and showing off her baby bump. Flower girl Paisley (Nickson’s 6-year-old daughter from a previous relationship) wore a pink ballgown and a flower crown atop her hair, but everyone else in the bridal party wore all black, along with the guests.

“I know that’s very untraditional, but I like the picturesque feel of it all,” Graf says of the bold color choice.

Big Brother head of casting Robyn Kass officiated the wedding. “We wanted it to be somebody that was a part of the special process that even brought us here,” Nickson explains.

“I’m thrilled to have officiated Jess and Cody’s wedding,” Kass tells PEOPLE. “I’m just so happy for them.”

Image zoom Jessica Graf and Cody Nickson Angelica Marie Photography

Once they said “I do,” it was time to party — and the newlyweds made sure their friends and family were well-fed with a donut wall that doubled as a seating chart, dinner catered from Texas Road House (Nickson’s favorite restaurant), a popcorn installation, a four-foot-tall cake by Frost It Cakery and late-night pizza by Big Mama & Papa’s. (Plus an open bar from Plant Based Mixologist serving everyone but the pregnant bride.)

Angelica Marie Photo photographed the affair, which was planned by Amber Events and with rentals from Papillon Rentals and White Lilac Rentals, and flowers by XO Bloom. Leo Cabal was the videographer.

For their first dance, the couple waltzed to “Shut Up and Dance” by Aaron Watson.

“He sang it to me when we were in the Big Brother house, and we danced to it, and, it just always sat in the back of my mind as one of our special moments,” Graf explains.

The couple met during Big Brother 19 in 2017 and went on to win season 30 of The Amazing Race.

“There was a long time in our relationship where everything we knew about each other, the outside world also new,” Graf says about their time on Big Brother. “If you were a live feeder, there were no secrets. It wasn’t until we finally got some alone time outside of the house where we could start getting to know each other beyond what everyone else knew, and I think that was pretty special.”

What’s next? First, a honeymoon at the Four Seasons in Bora Bora, before they settle into their new house, currently under renovation, in Nickson’s home state of Texas. And, of course, their baby on the way.

“In five years I am going to be on baby probably number three and exhausted. And, hopefully still pretty,” Graf jokes.