Patton Oswalt shares a moving tribute on the day his late wife's new book is published.

Nearly two years after her tragic death, author Michelle McNamara's final book was published today.

To much of the world, McNamara is best-known as the late wife of Patton Oswalt. But she had her own outstanding career as a nonfiction writer long before they met.

At the time of her death, McNamara was working on an investigative book about the Golden State killer. That book, "I'll Be Gone In The Dark," was finally published on Tuesday. Oswalt, who wrote the book's afterword, was instrumental in helping guide it to completion. Though McNamara had finished much of it before passing away in her sleep, Oswalt leaned on friends and colleagues to bring it home. "It was her book and it’s an amazing book," he said. "I wanted to do right by her."

Oswalt posted a picture to his Twitter account of him laying the book at McNamara's grave, with the note: "You did it, baby. The book is excellent, the writing brilliant. You tried to bring kindness to chaos, which was your way."

The book quickly shot to the top spot in Amazon's memoir section.

Oswalt has gone through a very public grieving process over the death of his late wife. But today, he's celebrating her work

Ever since losing McNamara, Oswalt has been very public about the toll her shocking death has had on him and his young daughter. Rather than putting a happy face on the tragedy, he was open about his perfectly natural, drawn-out grieving process. Being a comedian, Oswalt worked several jokes about his imperfect recovery process into his latest Netflix special that blended comedy with the agonizing pain of loss.

Slowly but surely, Oswalt has found his way to happiness, marrying actress Meredith Salenger last year. He obviously hasn't forgotten Michelle though, using his public platform to celebrate her life and her work. Fans shared an outpouring of support across Twitter, just as they have through each stage of Oswalt's grieving process.

After bravely sharing his grief and slow recovery, Oswalt is now showing us how to remember.

By letting the world into his painful grieving process, Oswalt revealed a level of vulnerability and real human strength that we are rarely see from public figures.

As he carries on in the next stages of his life, Oswalt is now showing the world how to continue living while still honoring the memory and legacy of those we've loved and lost.

McNamara brought him years of great happiness and he's using his celebrity to share her talents with the public. "It was a total commitment. … He's just been a real champion," said HarperCollins editor Jennifer Barth.

Everyone faces death and loss — but it's up to us to choose how we respond. Great mentors like Oswalt help show the way.

We all face death in the loss of others and ultimately in ourselves. Yet even as arguably life's only true certainty, we still often struggle to process the inevitable. Being open about the painful cost of losing a loved one can be an invaluable resource to those who are going through a similar experience and to those who may face it down the road.  

Patton Oswalt and those who were close to McNamara are also showing us that there can be positive ways to celebrate those we have lost and to keep their memories alive for years to come.