Mom Pens Heartbreaking Letter to 4-Year-Old Daughter Who Died of Cancer

— -- A Virginia mom is hoping to raise awareness of pediatric cancer by sharing a tearful video of herself reading a letter she wrote to her recently deceased daughter.

"The day that she passed, I wrote it that morning - after I got back from the hospital," Lindsay Rhoades, of Herndon, Virginia, told ABC News today. "I read it at her service. I've written letters to Kate for a long stretch of time, but this particular letter I thought about all the things I wanted to say to her if I had the opportunity to say them to her."

Rhoades, 39, said her daughter Kate was diagnosed with acute lymphoblastic leukemia in the summer of 2013 and completed her treatments in September 2015.

But on Jan. 11 blood work revealed that Kate had relapsed and one day later, she died at Inova Fairfax Hospital in Falls Church, Virginia. She was just 4 years old.

"She did so well through treatment and she was perfect, so this was truly the ultimate shock," Rhoades said. "It was absolutely the most gut-wrenching [feeling].... There's a lot of guilt wondering if there's something we could’ve done differently ... and utter disbelief because she was our only child and she just started living.

"She was an angel," Rhoades added. "She was very patient, very gentle, very studious, very, very sweet. She had a big place in her heart for other people that didn’t feel well.... She was also funny - so, so funny. She would’ve done big things, I think."

On Feb. 5, Rhoades said Mike Gillette, founder of The Truth 365, a social media campaign for children fighting cancer, encouraged her to appear in one of his videos, after hearing her read a letter she wrote to Kate at her funeral. It reads, in part:

"Our Dearest, Darling, Kate,

"Did you know how much we love you? How many times a day did we tell you while we kissed your sweet cheek? If you knew even half as much as we hoped you would, then we did our job as your mommy and daddy.

"... We always wanted to be your mommy and daddy, you know. We dreamed about who you would become, what music you would like and who your first crush would be. I was secretly excited to find out who your first boy band would be so that I could pretend to like their music for you. We wondered how you would like school. Would you be athletic or studious? Where might you go to college and what would you study? This nightmare of never knowing who you will grow up to be will haunt us for the rest of our lives - forever for, they say.

"Since 4 is the forever we were given, I'd say it was a mighty fine 4, and without even knowing it, we spent the last four months building one heck of a lifetime together.... Kit-Kat, we promise that your life will be remembered for the cheerful, bubbly, way you lived, and that your beautiful spirit will be with us forever.

"... God only knows how we'll get along without your sweet face, adorable voice and cheeky grin. When you see him, ask him if he has any pointers on that. Then come by and share them with us. Maybe through a pretty snowfall out back this winter, a breezy day hammocking this spring and the smell of the honeysuckle you loved in our backyard this summer, or as a beautiful fox in our front yard. Come visit us, baby, We know you can't stay. Just promise you'll come...."

The video, titled "Letter to Kate," has been viewed more than 124,000 times since being posted on The Truth 365's Facebook page.

"The part toward the end, we talk about how we will not let her passing be in vain," Rhoades said. "We want to to raise awareness for pediatric cancer and ultimately for a cure. When she passed, I promised we will not let it be for nothing. We will do big things in her name."