"I'm still crying because I won," the winner tells PEOPLE of the moment he was announced as the Project Runway winner

Warning: Spoilers ahead for the Season 18 finale of Project Runway.

The winner of Project Runway Season 18 is here!

On Thursday night, viewers of the fashion design series watched as fan-favorite, Geoffry Mac, 42, was named the winner of this season’s Project Runway — beating out fellow finalists Victoria Cocieru, Geoffrey Mac, Nancy Volpe-Beringer and Sergio Guadarramain — in a close-call final runway show.

Tennis champion Serena Williams served as the guest judge for the final runway challenge while the show’s weekly judges, Brandon Maxwell, Nina Garcia, Elaine Welteroth, Karlie Kloss and mentor, Christian Siriano, also worked together to help choose the series winner.

Project Runway - Season 18

The veteran designer, who has worked in the industry growing his personal brand for the past 20 years, was totally shocked by his win after wowing the Project Runway judges with his bold and sparkling avant-garde collection at New York Fashion Week. In fact, when his name was called, he thought he was being sent home.

“They just brought everybody out … and they said ‘Geoffrey’ and then there was what seemed like a five-minute pause from Karlie,” Geoffrey tells PEOPLE of his winning moment. “‘You are the winner…'”

In shock, the designer says he instantly started crying, “I’m still crying because I won.”

Project Runway - Season 18

He continues, recalling the judges’ critique of the runway show. “It was absolutely mind-blowing to have Serena Williams talking about my work. I’ve followed her forever so it was intimidating and I was terrified if she’d like it or not — It was a little star-struck and it takes a lot for me to feel that way. But she’s just such an overall icon.”

The winner affectionately called his collection “Purple Heart,” inspired by his father who served in the military and received three of the respected honors. Geoffrey, who now has a good relationship with his dad, explained that things were more complicated when he was growing up — revealing difficult memories with viewers on the show.

“It got really deep into issues with my father, and stuff all throughout [the show], which I struggle with constantly. It was all very much out there, so I just had a lot of getting through to do,” he says.

But despite growing up with the rigor of a military family, Geoffrey found his independence in the ’90s rave culture and followed his passion in the world of fashion design. With a design range stemming from stage costumes to luxe ready-to-wear, the designer — who has worked with celebrities such as Lady Gaga and Britney Spears — stayed true to his dark aesthetic and presented a unique collection of loud geometric puffer jackets and sleek coats, chain-mail dresses, ornately embellished sets and re-vamped streetwear looks for both men and women.

Project Runway - Season 18
Project Runway - Season 18

And while his bold collection radiates confidence, Geoffrey admits that the overall experience of being on Project Runway was very much out of his comfort zone, explaining that self-identity is something he has always battled with.

“I’m a very private person. People don’t think I’m shy, but I’m pretty painfully shy. I don’t get out much. I’m not very social. My friend circles are really small. So the idea that it was public … is why I like to be more private,” he says.

Even though it was harder for the Brooklyn-based designer to come out of his shell, he describes winning as one of the “most proud” moments of his life.

“I was able to call my father … and he was crying. And the only other time I’ve ever seen him cry in this world was when he lost his golden retriever when I was in fourth grade,” Geoffrey recalls. “He was crying on the phone and that was just a life-changing moment to get that level of pride from my dad.”

Apart from his own collection, the designer — who also specializes in original latex creations — applauded Cocieru for her versatile runway show boasting chic separates with her signature asymmetrical designs.

“Victoria, I always felt like she was my number one competitor from the beginning, just because she can turn out looks so quickly and she’s got a really strong aesthetic,” he says of the Moldova-born designer. “It’s very wearable and I felt like the collection she brought was strong. It was, the separates and coordinates was really a smart idea for sales.”

As for what’s next for the designer? Geoffery tells PEOPLE he is leaning towards creating a men’s ready-to-wear collection, but also still wants to focus on custom design and creating looks for women.

“I’m trying to meet with a bunch of people and get advice and then see what I connect with the most, what sounds the best. I’m looking for obviously whatever’s the most successful route, but it also needs to be where my passion is,” he explains. “My passion is in custom, so that’s for sure going to be happening.”

And in addition to working on a new line of clothes, the designer says he is also coming out with his own custom unisex fragrance called G.

“It was a fragrance that I made about 10 years ago at Henri Bendel — I had lost the recipe for it but I had a little saved so we ended up replicating it, tweaking it a little bit to something even better,” he explains.

The new Project Runway winner is definitely keeping busy but is looking forward to slowing down and celebrating with his family.

“My niece is in Maui with my sister. So I’m going there in March for my birthday,” Geoffrey says, explaining that before he could even tell his 12-year-old niece that he won the competition, she was already so proud of her uncle. “I was on the phone with her and she’s like, ‘I just have to tell you that like I’m so proud of you’ — and she couldn’t come up with the word and she’s like ‘pride of you.'”

As the winner of Project Runway, the longtime designer received a $250,000 grand prize courtesy of Bluprint, a feature in ELLE magazine, the chance to be featured in a Bluprint digital series, $50,000 from show sponsor Pilot and a coveted mentorship with CFDA (Council of Fashion Designers of America).