Doctors Expected Fiancée of NFL Linebacker to Beat Ovarian Cancer, but She Died Suddenly, Friend Says

Nobody saw it coming, least of all NFL linebacker Tony Steward

Steward’s college sweetheart and fiancé Brittany Burns died on Monday, less than two months after being diagnosed with terminal ovarian cancer and just weeks after the Buffalo Bills player asked her to be his wife.

Her sudden death came as a shock to Steward, Burns’ family and their close friend Tim Russell.

“It all just happened really fast. There wasn’t even time to worry about a time frame, because it was a blink and it was over,” Russell tells PEOPLE. “Out of nowhere it was just getting bad fast and [doctors] couldn’t get ahead of it. They were trying all these new things. They didn’t know how much time she would have, but they didn’t expect it to be this sudden.

"No one could have seen this coming. Even the doctors were blown away by how fast it happened.”

Russell, Steward’s best friend, says that Burns began complaining of stomach pain and fatigue in October. A doctor found cysts on her ovaries and gave her medicine, but, he says, that wasn’t the end of it.

“A whole month went by and one night, we were all hanging out, and she just starts screaming like she was in the worst pain of her life,” Russell tells PEOPLE. “So we drove her to the hospital, they did surgery [on her cysts] and they found a big tumor.”

Burns was diagnosed with ovarian cancer on Dec. 9. Russell says doctors expected Burns to “take some chemo” and “kick it.”

“For the first couple nights [Steward and I] didn’t go to sleep at all,” the 23-year-old says. “One of us was always at the hospital with her.”

Burns’ health went up and down in the weeks between her diagnosis and death. And Russell says the former Clemson University rower passed away just when her family thought she was improving.

“She was doing better and then she just passed away. We thought she was getting better and it was looking up. Then, out of nowhere, it wasn’t,” he says. “I would have never thought in a million years that it would happen like this. No f—— way.”

She died at her family’s Delaware home.

“I don’t know what happened exactly. Tony told me she was doing fine and then she just passed away,” Russell says. “We’re destroyed, and we’re pissed and we’re angry that the person that we loved so dearly is gone.”

He spoke through tears as he described Burns as his family: “We argued like brother and sister, we loved like brother and sister.”

“She’s one of the biggest parts of my life, and the biggest part of Tony’s life. She was really important. You gotta know how beautiful she was,” he says.

Now, Russell is with Steward and Burns’ family in Delaware, preparing for her funeral on Saturday at the Westminster Presbyterian Church.

“We’ve all been just staying together, laughing whenever he can,” Russell says of himself and the group. “Basically, we just spend as much time together as much as possible. Obviously we’re all in pain. We’re just staying together and we’re going to stay together until it’s all better. We just hang out all day long; cry next to each other, and laugh next to each other.”

Before her death, Burns and Steward launched a charity fundraiser, “ Britt and Tony’s Fight Like a Girl Campaign.” Russell says he, Steward and Burns’ family now run the CrowdRise fundraiser.

“All the money that was donated, it goes to research ovarian cancer,” Russell says. “We’re just getting our foot in the door in this fundraising thing, but it’s going to grow. "It’s not going to be a one-and-done thing.”

As of Thursday, the fundraiser, on CrowdRise, has raised nearly $23,000.