"He's the most determined person I know. If anyone can push through this, it's Brett." Meg Alexander tells PEOPLE

Meg Alexander and Brett Greenhill’s joint bachelor/bachelorette party ahead of their February nuptials was shaping up to be one of the best weekends of their lives.

On Friday, Dec. 2, the couple surrounded themselves with their closest friends and family in Naples, Florida, where Alexander’s mom lives.

“It was so much fun,” Alexander, 29, tells PEOPLE. “Everyone had a blast.”

But the celebration took a tragic turn on Saturday when Greenhill, 39 — who was playing football with his friends on the beach — decided to go for a swim.

“Brett went into the water and all of a sudden my friend Kelsey says, ‘Why is Brett doing that? Why is he floating like that?’ ” Alexander tells PEOPLE. “I was like, ‘I don’t know, he’s a goofball’ and she went to check on him.”

Seconds later, Alexander heard screams.

“We all ran to pull him out of the water and [Kelsey] was stabilizing his head,” Alexander recalls. “My mom called 911.”

Meg Alexander and Brett Greenhill
| Credit: Vic Bonvicini

Kelsey Rice, a nurse and one of Alexander’s best friends, knew something was immediately wrong when she saw Greenhill in the water.

“I grabbed him, flipped him over and he said, ‘Help me, Kel. I can’t move,’ ” Rice tells PEOPLE. “It went from an incredible weekend to devastating.”

Lying down on the sand, Greenhill looked up at his fiancée and said, “I can’t feel anything. Meg, I love you so much and I’m so sorry. I love you so much,” Alexander recalls.

She quickly replied, ‘I love you. Don’t be sorry. We’re going to figure out what’s wrong with you.’ ”

Paramedics arrived and air-lifted Greenhill to Lee Memorial Hospital in Fort Myers, where they learned that he became paralyzed from the neck down after hitting his head on what they think was a sandbar, according to Alexander. Doctors then told her that her fiancé has a 1 percent chance of mobility.

“We’re holding on to that 1 percent because if anyone will do it, it’s Brett,” she says. “He’s the hardest-working person you could ever imagine.”

Credit: Vic Bonvicini

Love at First Sight

In May 2014, Alexander, who had just moved to Atlanta, Georgia, saw Greenhill at her apartment complex’s pool.

“He was really cute,” she recalls. “I swam over to him and said, ‘So this is probably the worst line ever, but I just want to tell you that you have really pretty eyes.’ ”

He looked back at her and said, “Well, so do you.”

“I said, ‘No way. You don’t know even know what color they are,” Alexander says. “So I closed my eyes and he said, ‘Yes, I do. They’re blue.’ ”

The duo got to know each other, quickly learning that they were both passionate runners. They decided to go on a run for their first date.

Their second date was spent volunteering at a local men’s shelter, followed by dinner. Alexander had a feeling there would be many more dates to come.

“I said to him, ‘I’m going to marry you some day or someone exactly like you,’ ” says Alexander, who is an account manager. “When you know, you know, and I just knew…I still know.”

On Jan. 17, 2016, Greenhill proposed to Alexander at the end of a run.

“He was no nervous,” Alexander recalls. “The diamond in the ring was his grandmother’s — it was so special.”

Brett Greenhill and Meg Alexander
| Credit: Courtesy Kelsey Rice

Alexander says that Greenhill, an accountant, is the most selfless man she’s ever known.

“If you know Brett, you know you can rely on him for anything,” she says. “He would give anyone the shirt off his back. That’s how he lives his life.”

It’s that spirit and energy that makes this devastating incident all the more tragic, she says.

“It’s not like anybody would ever deserve this, but it’s mind-boggling to me,” she says. “I know everything happens for a reason, but I don’t know what that reason is yet.”

Planning for the Future

The couple, who has a strong belief in God and their shared Christian faith, decided they would only move in together after they were married on Feb. 11, 2017. Invitations were going to be sent out after their celebration weekend in Florida.

“Our entire world has taken a very different turn than we thought,” says Alexander. “We had the trip of a lifetime planned for our honeymoon.”

The couple was going to travel to New Zealand and rent a camper van that they were going to drive through the South Island.

Now, Alexander is trying to rewrite their script.

A GoFundMe page, which has raised more than $84,000, was created to help with medical bills, future procedures, rehabilitation and necessary adjustments to their home.

“I know it’s going to be an uphill battle, but it’s been amazing to see the people who have come out to support us,” she says.

Brett Greenhill and Meg Alexander
| Credit: Vic Bonvicini

Greenhill is currently in the ICU and temporarily unable to speak. The couple has had to figure out a new way to communicate. Doctors tell Alexander that her fiancé will regain the ability to speak again.

“I go through the alphabet and he’ll tell me what letter to stop on so I can write words out,” she says. “The first thing he said to me was, ‘I love you,’ and the second thing he said was, ‘Please be patient with me.’ ”

She adds, “He knows where he is and what happened. I can’t imagine what is going through his brain right now. He’s so smart and analytical.”

Alexander, who hasn’t left her fiancé’s side at the hospital, says when he’ll be transferred to the Shepard’s Center in Atlanta for rehabilitation when he’s well enough.

“It’s only 15 minutes from our house, so we’re very lucky,” she says. “He’s the most determined person I know. If anyone can push through this, it’s Brett.”

Although their wedding is on hold for now, Brett will still be moving in as the couple begins their life together under the same roof.

“Obviously, this situation is extremely trying,” she says. “But together we can get through this. I know we can.”