“I remember at a point before the Euros, I was thinking ‘can I continue to do this?’. I had no escape,” Furness tells BBC Sport NI as she opens up about her mental health journey.
“It was a really, really tough decision, but the little girl in me wanted to play at a major tournament, to go and experience that.”
She boarded the plane to Southampton, and, with her customary smile, made history stepping out against Norway in Northern Ireland women’s first match at a major tournament.
But behind the outgoing persona, things were brewing.
Midway through the tournament she wanted to go home for the sake of her mental health.
“You might think it’s crazy, but I just wasn’t happy,” says Furness.
“Everything just seemed so in place on the football side, it was going really well.”
In the background, everything wasn’t as rosy.
Off the pitch, she had been processing the end of a long-term relationship alongside her father’s illness.
Coupled with the high-intensity environment of a major tournament, she had reached breaking point.
“Personally, I wasn’t happy with myself in the environment,” Furness adds.
“Then you start to question, why? Why am I doing this? Why do I feel like this?”
After shedding some tears, she composes herself to recall the conversations as team-mates attempted to persuade her to remain in camp, rather than walk out on a campaign that was the pinnacle of all their international careers.
Furness and her fellow players talked long and deep, looking out from their hotel overlooking Southampton’s sun-kissed harbour. In the end, she was convinced to stay.
“I’m glad I did stay because I go back to that moment with the fans at the end, and thinking that was all worth it,” she says. “That’s the special moment I take away.”
But when the singing stopped, when the dancing was done, a decision remained.
Furness had managed to get through the tournament, but her mind was made up. She needed to take a step back from a team she loved so much.
After the tournament, she had conversations with staff about “how I was feeling, and how I was made to feel” and why she couldn’t carry on.
“It was tough to get across how I felt, and how mentally I was feeling,” she says.
“I did blame myself for a lot of that. Before I’d spoken to somebody and made sense of it, you do just blame yourself.
“I love representing Northern Ireland, and taking that risk of stepping back, never knowing if I’d step back in, was one of the biggest decisions of my life.
“Two years on you can tell it still touches and it still means a lot, but it’s one I can comfortably speak about now. I’m in a much better place for that.”