HARTFORD, Conn. (CBS News) — A Connecticut woman with advanced breast cancer married the love of her life at a Connecticut hospital right before Christmas, then passed away 18 hours later.

Heather Mosher was dressed in her wedding gown and lying in bed wearing an oxygen mask as she and David Mosher said “I do” Dec. 22 at St. Francis Hospital and Medical Center in Hartford. The 31-year-old died the next day.

The couple fell in love after meeting at a swing dancing class in 2015.

David Mosher told news organizations that on the day he planned to propose, Dec. 23, 2016, Heather was diagnosed with cancer. He went ahead with the proposal.

“She didn't know I was going to propose to her that night, obviously, and I said to myself, you know, 'She needs to know that she's not going to go down this road alone,'” he told CBS Hartford affiliate WFSB.

He said the two went on a carriage ride and he proposed to her under a street light.

By the fall of 2017, Heather's cancer had spread.

“We found out it was in her brain and a couple months later, she was on life support with a breathing tube,” David said. “She was tough. Anyone else would have given up a long time ago. The doctors even said we don't know how she's still here.”

They originally planned to marry on Dec. 30, 2017, but doctors urged them to do it sooner, and they tied the knot at the hospital on the 22nd, with loved ones gathered by Heather's bedside for the ceremony.

Their planned wedding day ended up being the date of her funeral.

“We were losing her as we were all standing there thinking to hold on to this, because it was it. … What we were seeing, what she was giving us, what she was giving him, was the last of what she had to give,” said Christina Karas, a bridesmaid who captured photos of two getting married at the hospital.