Sean Fredrickson and His Family Were Killed on First Summer Vacation, Wife Reveals: 'They Died Happy'

The tragic plane collision that killed Sean Fredrickson, his son Hayden Fredrickson and his stepchildren Sofia and Quinn Olsen happened during a rare family vacation, the PGA Professional's wife tells PEOPLE.

"My husband's in the golf industry and time off in the summer is extremely rare. So we literally never had summer vacations. This was the first time that we had gone anywhere in the summer," April Fredrickson, 46, tells PEOPLE, explaining that the family usually waited until the end of the golf season and Labor Day to take any trips.

But this year, April said her husband was looking forward to having time to "decompress" and took off the Fourth of July weekend.

So the family traveled from Lake Oswego, Oregon, where Sean was the head PGA at the Oswego Lake Country Club, to his parent's house in Spokane, Washington, for the holiday weekend. On Sunday — the last full day of their vacation — the group went to the nearby Lake Coeur d'Alene to "play around and do something a little different," April says.

The trip seemed like the perfect opportunity to take a ride on a seaplane over the scenic lake — something April says her husband had been wanting to experience.

courtesy april fredrickson April and Sean Fredrickson

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April, who had already been on a seaplane, opted to sit the 20-minute excursion out, she says, and "decided just to stay and wait for them."

But as she waited for her family to return, April found 20 minutes stretching into 40 minutes, and then an hour, and then an hour and 15 minutes.

"I left to go see if I could get ice cream or something," she tells PEOPLE, "Cause I was frankly just kind of bored sitting there."

But when April came back, the plane was still nowhere to be found.

"And that's when I saw the two sheriffs," she says, "And then the sheriffs came and got me and told me that there had been a collision, and that they didn't know much at the time and that they were just kind of waiting to find the plane."

April says as her family left her for their flight, "it went through my mind that this might be the last time I see my family," but it was just a fleeting thought.

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"And it was more of a jokey kind of thing, but it crossed my mind," she says, adding that "anytime you send your entire family on something that seems kind of risky, you know, that goes through your mind. And so it did."

April explains that she took a few photos of Sean, Hayden, Sofia and Quinn "literally right before they got on the plane," and as she snapped the pictures, she thought, "you know, this might be the last time I see my family."

"But again, not being serious about it, just kind of laughing and joking about it," she says, adding that they took a "jokey picture" of the foursome social distancing and standing six feet apart.

Not knowing that it was their last moment together as a family, April says she had everyone do a group hug as they started to board the plane.

courtesy april fredrickson April and Sean Fredrickson

courtesy april fredrickson April and Sean Fredrickson

"Not like a serious group hug. It was more me just saying, okay, give mom a hug," she recalls. "But they were already like halfway on the plane. And I kinda just gave them a hug, sent them on the plane and started taking pictures."

April says she is "committed to getting past this" tragedy and is "focusing on the fact that it was immediate for them."

"I'm sad that I'm not going to be able to watch movies with my little guy anymore. I'm not gonna take my daughter to 'say yes to the dress,' which we had talked about and planned on," she tells PEOPLE.

"Like, there's so many things that I'm sad for, but at the same time, they died happy, they died on a plane doing something that was really exciting for them and they didn't know. And so I'm just so thankful that that's how it happened."

"I'm trying to remember that. And then when I get that pit in my stomach, that burning, that just kind of that anxious feeling, I'm just trying to tell myself that I'm going to choose life and I'm going to take this opportunity and I'm going to create my life."

"This is my next chapter. And it's really up to me to figure out what that's going to be. And I'm going to just do the best I can to have a life I want," April tells PEOPLE. "There's nothing else I can do."

courtesy april fredrickson Fredrickson family

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April's next chapter will include honoring her family's memory. She tells PEOPLE that she plans on establishing memorials for each of her children, as well as Sean, based on their passions.

Sofia, 15, played lacrosse and worked at StarCycle, so April hopes to create a memorial ride at the cycle studio to benefit her daughter's lacrosse team.

Quinn, 11, loved playing video games with his friends, April says, adding that she hopes to eventually host a big game night for his friends to remember him.

courtesy april fredrickson Sofia and Quinn Olsen

For her husband of nine years, April is "hoping to work with the PGA to establish a memorial golf tournament for" Sean.

"And if they'll let me, I would like to take whatever profits or proceeds there are from that and basically earmark that money for diversity and inclusion initiatives at the PGA," she says.

"Because Sean was a really good mentor, but he also understood that the game of golf is not necessarily accessible to everyone," she says, adding that her husband "really tried to mentor women and to make sure that women get the opportunities that they earn and to try and, you know, put women in a position to have more head pro positions."

April adds that a golf tournament raising money for diversity and inclusion would "be the right thing to do."

"I think that would really honor his memory," she says.

• Reporting by RACHEL DESANTIS