Runner, 33, Among First with Down Syndrome Ever to Finish NYC Marathon: 'Victory Dance at the Finish Line' (Exclusive)

Last weekend Kayleigh Williamson, 33, made history as one of the first women with Down syndrome to complete the New York City Marathon. Looking back on the memorable day, her mom Sandy Williamson — who ran alongside her daughter — tells PEOPLE the 10-hour, 9-minute journey was filled with endless dancing, hugging and high fives.

"New York changed the way I saw my daughter," Sandy, 56, explains. "Every time she heard music she stopped to dance. It was very emotional for her at the end, the last two miles."

"But then someone turned up music on their phone and she would dance a little. Then she would cry," she continues. "Her muscles were sore and they were bothering her. Things like that. But Kaylee didn't stop. She didn't want to give up."  

Kayleigh, crying as she recounts the experience to PEOPLE, says she'll always remember how she felt knowing she made history. "I am a diva," she says. "The whole race I was always fixing my hair. I did a victory dance at the finish line."

The Austin, Texas, native isn't new to the world of running. In fact, Kayleigh has also completed the Boston marathon, 21 miles of the Austin Marathon and 20 half-marathons.

Kayleigh's running journey began in 2017. "It was at about the same time my mother was diagnosed with Alzheimer's," Sandy says. "So I implemented some healthy lifestyle choices. We just started running and I was already running and Kayleigh wanted to do some races with me."

"My mom used to tell us she escaped from the nursing home and had traveled to all these places like California and Colorado," Sandy continues. "So what we started doing was finding races in those states to turn her temporary memory into permanent ones. Kayleigh would take her medal back and show it to my mom."

Since then, Sandy says her daughter has fallen in love with running. Up next Kayleigh and Sandy are training for a Turkey Trot on Thanksgiving Day, along with half-marathons in December, January and February.

"I like to run because it makes me feel happy," Kayleigh says.

Kayleigh adds that she not only ran the NYC marathon to make history but also to honor her grandmother, who died in 2021. Growing up she says her grandma always talked about taking her to NYC to see the holiday lights. This marathon was Kayleigh's first time in the state.

"On the back of her shirt it said, 'Running in memory of my grandma, memories matter, Alzheimer's awareness,'" Sandy says.

Around mile 8, Sandy says her daughter stopped her to remind her that she too, was running in honor of her mom. "My daughter has this ability to just see into people's hearts," she continues. "That for me was that pivotal moment because during the race, she kept saying 'Mom you're running for grandma too.'"

On the way back home to Austin, Sandy and Kayleigh had a layover in St. Louis. After they landed, an airline employee asked if Kayleigh needed a wheelchair. "No, she just did a marathon," Sandy said. "I said, 'She's one of the first women with Down syndrome to do the New York City Marathon.'"

The employee announced the news to all of the passengers waiting at the airport.

"They announced it on the plane, too," Sandy continues. "Then they had Kayleigh go up to the cockpit to see inside and take pictures with the stewardess. We had people on the plane say they watched her on social media."

She adds: "It was a little surreal. But Kayleigh being the diva that she is just wanted to give everyone hugs and kisses."