While Shelly, who had starred in such indie hits as Hal Hartley's The Unbelievable Truth, was happily married to marketing company owner Andy Ostroy, she had trepidations about balancing her work with motherhood, which she wove into the script.
"The central theme of the film is what Adrienne felt in her own life," Ostroy, 56, tells PEOPLE. "This story is about a woman who is afraid. It's about a woman who has real challenges and fears in life.
"There's a moment where Keri Russell finds out that she's pregnant and she's not happy. The doctor even says, 'Uncongratulations.' That was pretty much what Adrienne had feared – that would she lose her identity as a person and her ability to work."
But when Sophie was born in 2004, Shelly's entire outlook changed, says Ostroy. "Once she saw Sophie, it was incredible. The love she had for that child was just monumental. Her fears vanished. She just adored that little girl so much."
Shelly melded motherhood and work perfectly, he says. "When she started editing the film, she would be in her old apartment where she went to write," he says. "Sophie would be crawling around the floor while she was editing and working on the script."
"She was joyful about being able to achieve her dreams and still be a mother who was still madly in love with her child. She finally had it all."
That all ended on Nov. 1, 2006, when Shelly, 40, was murdered by Diego Pillco, a 19-year-old construction worker, who killed her in the apartment where she worked, staging it to look like a suicide. He later told police she had caught him trying to steal from her purse. In 2008, he was sentenced to 25 years without parole.
Shelly's loss left Ostroy and their daughter devastated. "It was the worst thing that could ever happen," he says.
For more on Adrienne Shelly, pick up this week's issue of PEOPLE, on newsstands Friday.
Night and Day Pictures
Wanting to further her legacy, a month after her death, Ostroy created The Adrienne Shelly Foundation to support women filmmakers.
"For a few weeks after she died, I had a lot of people who were asking where they could donate money in her honor," he says. "It was too soon. I didn’t know. Those first few weeks were harrowing and I wanted to think about it."
"When my head was able to get clearer, I thought, 'What would Adrienne want? Who would Adrienne want to help?' Other struggling women filmmakers."
He did just that. Led by board members including Paul Rudd, Cheryl Hines, Michelle Williams and Keri Russell, the foundation has partnered with top filmmaking institutions including the Sundance Institute, the American Film Institute, IFP, Women in Film, the Tribeca Film Institute, Columbia University, Rooftop Films and Boston University, Shelly's alma mater.
The foundation has also awarded 60 production grants since its inception, including one to Cynthia Wade in 2007, who won an Academy Award the following year for her documentary Freeheld, which ASF helped fund.
"Adrienne would have been so proud," he says.
The Success of Waitress Lives OnWaitress premiered at the Sundance Film Festival in January 2007, to huge acclaim. "It was the big talk of Sundance that year," says Ostroy.
Fox Searchlight Pictures bought rights to the film hours after it debuted, with Waitress hitting theaters four months later.
Now, almost 10 years after Shelly's senseless murder, Waitress, which opened April 24, has become a hit musical on Broadway, scoring four Tony nominations on Tuesday.
Ostroy and his daughter, now 12, have seen the show and think it's "a wonderful addition to Adrienne's legacy," he says. "It's one of the many things she has to remember about her mother as she is growing up."