And he knows that no lawsuit, finger-pointing or public outrage can change any of it.
Rather than allow their grief to manifest itself as anger or legal vengeance, he and his wife, Alison, have devoted the last 12 months to making sure something beneficial comes from their very public tragedy.
"It was not our first impulse to go out and hire a lawyer. That's not the way we're wired," Barry Sullivan said. "We never really felt a reason to pursue any kind of legal action. Why would you do that? ... We didn't want to take resources and energy away from other positive things that might happen by tying up people with lawsuits and other actions."
Declan Sullivan, a 20-year-old business major from suburban Long Grove, was working for the school's athletic department when he went up in a lift to record football practice on Oct. 27, 2010. Though he expressed concerns on social media about the severe wind advisory that day, the team's staff said it was unaware of any warnings.
As gusts reached 53 mph during practice, Sullivan's lift crashed through a fence and landed on a street.
The Indiana Occupational Safety & Health Administration fined the university $42,000 for safety violations stemming from the accident.
Forbes.com last year estimated it could cost the university $30 million if Sullivan's parents sued. The mere suggestion seemed unfair to Declan's father.
The family — whose ties to the campus and its sister school, St. Mary's College, go back several decades — witnessed how much his death distressed the Notre Dame community and had no desire to compound that grief with a lawsuit or public criticism, Barry Sullivan said.
A week after the accident, the university's president, the Rev. John I. Jenkins, sent a letter to students and alumni, expressing his sorrow and accepting personal responsibility for the accident. "Declan Sullivan was entrusted to our care, and we failed to keep him safe," Jenkins wrote.
The letter's sentiment set the tone for Declan's parents' dealings with the university, Sullivan said.
"We saw people that were obviously suffering," he said. "They felt a great sense of responsibility for what happened. How could we add to their pain with displays of anger or anything like that?"
The family also worried that any public comments would interfere with the university's internal investigation, Barry Sullivan said. If the examination was compromised, an opportunity to learn from the mistakes surrounding Declan's death could be lost forever.
The university's investigation found "no one acted in disregard for safety" the day of the accident. Rather, a "sudden and extraordinary" wind and long-standing policies led to Sullivan's death, officials said.
According to the report, the football program's policy was to keep the videographers off the hydraulic lifts if the winds reached more than 35 mph. The weather data accessed by the staff never crossed that threshold, officials said.
In keeping with international standards, the lift industry typically recommends grounding the equipment when winds exceed 28 mph.