Parents who lost 2 children in alleged nanny attack explain how creativity helped them heal

— -- The parents of two children allegedly killed by their nanny inside their New York City home in 2012 have penned new essays opening up about their grief and their journey to recovery.

Marina Krim, who walked in the family's Upper West Side apartment on that otherwise ordinary afternoon to find her children Lulu, 6, and Leo, 2, dead in a bathtub, said that in the weeks following Lulu and Leo's deaths, she noticed “magical things happened," describing her senses as “being awakened.”

“I noticed a piece of street art on a construction site -- a stencil of a young boy holding a sign filled with colorful hearts. I instantly connected him to Leo,” Krim wrote in her new essay. “I felt that maybe the universe was trying to tell me something, that it was helping me to realize that there was a beautiful 'new' relationship waiting to be developed with Lulu and Leo.”

Krim was coming home from taking her then-3-year-old daughter, Nessie, to a swim class when she discovered her other children dead. Their nanny, Yoselyn Ortega, was charged with their murders and is awaiting trial. She has pleaded not guilty. Her next scheduled court appearance is May 18.

Ortega, a naturalized U.S. citizen who was born in the Dominican Republic, worked for the Krim family for two years and had been referred to them by another family, New York Police Department officials said at a 2012 press conference.

Krim’s husband, Kevin Krim, wrote in a separate essay that it was Nessie, now 8, who helped him move forward in the immediate aftermath of Lulu and Leo’s deaths.

“When you wake up the first morning to a new and terrible world, what do you do? I didn’t feel like I’d ever want to do anything ever again,” Kevin Krim wrote. “But then little Nessie, our surviving child who was not yet 4 years old, looked at me and said, 'Daddy, I’m hungry.' And I knew I had to take care of her and Marina.”

The Krims wrote the essays for Option B, a website on adversity and resilience started by Facebook COO Sheryl Sandberg, whose husband, Dave Goldberg, died unexpectedly in 2015. The website takes its name from a new book on grief written by Sandberg and psychologist Adam Grant.

"Expressions of creativity continue to help us heal, rebuild, and thrive. In part, writing our stories for Option B was a natural way for us to not only remember Lulu and Leo and talk about Choose Creativity, but also help others survive and thrive in the face of adversity," the Krims said in a statement to ABC News. "We would have been happy to help simply because Sheryl and Adam are kind, thoughtful, and generous people and friends. We are also grateful to contribute to a well-researched and written book about the subjects we are asked about so often. It's a critical resource that everyone should read."

Marina Krim described other instances -- including hearing the theme song from “Peanuts” and receiving, with Nessie, a compliment from a stranger -- as being signs from Lulu and Leo.

“They showed me that there was still a way to connect with them,” she wrote. “It was an approach inspired by who they were and what they loved. It required creativity, always an important influence in my life.”

Marina Krim also explained why, on the first Mother's Day after her children's death, she decorated a wall in the family’s apartment with sand dollars she and Lulu had collected together from the beach on a family vacation.

“It was a simple way to express myself, feel present, and connect with Lulu and Leo on a really tough day,” she wrote.

The Krims have since had two more children, Felix, 3, and Linus, 1, and returned to New York City after embarking on a cross-country trip with Nessie in an RV.

Kevin Krim described the couple’s three living children as “genetically and spiritually half Lulu and half Leo.”

Both Marina and Kevin Krim wrote that the creativity that helped them in their healing inspired them to found The Lulu & Leo Fund and Choose Creativity, an organization that offers parents and schools a creativity curriculum based on 10 principles of creativity "that can help anyone thrive and build resiliency in all facets of their lives," according to its website.

“Marina and I shared the creative impulse to do something constructive in the face of the destructive effects of violence,” Kevin Krim wrote. “We started the Lulu & Leo Fund in those early days to honor their creative, too-brief lives.”

Sheryl Sandberg is a member of the board of The Walt Disney Company, the parent company of ABC News.