As a 16-year-old student on April 20, 1999, Miller went to the Columbine library on her lunch break to study for a test. The library would become the scene of most of the bloodshed that day. 

As the killers roamed in search of victims, she hid under a table. "I prayed (and) wondered what it would feel like to get shot," she said. "I never felt so afraid of my life."

Over the last 22 years, Miller has searched for ways to translate the horror of her experience into an uplifting message for others.

In 2006, Miller and Ashley Wiersma wrote the book "Marked For Life: Choosing Hope and Discovering Purpose After Earth-Shattering Tragedy." Miller serves as an advisor to the Onsite Foundation, a nonprofit that counsels survivors of mass shootings and others who experience trauma.

And now, Miller has posted an open letter on the foundation's site — addressed "Dear fellow survivor" — in response to the Boulder deaths and the mass shooting in Atlanta a week earlier.

"I am deeply sorry that I have failed you," the letter says. "That we have failed you. I am sorry tragedies like yours have become so commonplace. I wish I could erase the grief and sorrow that have now become a part of your story. This is not the way it is supposed to be.

"I want you to know you are not alone."

Miller has been to Boulder since the shootings, and while she has not yet met with families of victims, she said she wants to help in any way she can.

"We can't go back to who we once were," she said. "We now are living in a new normal. But this should not be the new normal."

In her letter, Miller conceded that it's hard to find words to say to those who have survived mass shootings that don't "feel small or trite."

"There is no manual for something like this," she said in the interview. "But I come with a heart that cares deeply, that feels what they're feeling."

Those in pain should know, she said, that "they're not alone, because I believe that healing takes place within community and that we desperately need one another, and that we're stronger together than we are alone