"The trauma after the war was almost worse than the trauma during the war was," he told CBS News national security correspondent David Martin.
He tried to pick up where he'd left off in college, but couldn't.
"I had nightmares, anxiety, panic. I didn't know why it was happening," he said. "I thought for a second that I had gone insane."
His service with the Marines had alienated him from normal, everyday life.
"I knew that nobody was going to be able to help me because nobody was going to be able to understand what was happening to me," he said. "I think that was the worst feeling."
His war story was no different from countless other foot soldiers. A roadside bomb came so close, it blew the door off his Humvee. One of his closest friends was killed in action.
It's the baggage carried by a new generation of veterans.
"A significant portion of veterans have turned to substance abuse as a way to self-medicate and deal with the flashbacks and the nightmares, says Tom Cray of the Rochester Outreach Center in New York.
Cray, who runs the private veterans center, says that 261 veterans of the wars in Iraq and Afghanistan have come in seeking help. That's 261 veterans just in the community of Rochester.
"By the time they get to us, they've almost hit rock bottom," he said.
For Stefanovic, the road to rock bottom was paved with the painkiller Oxycontin.
"The nightmares went away," he said. "The anxiety went away."
But he soon became addicted to the powerful painkiller.
He was arrested and eventually jailed due to his drug use. He was also charged with larceny, having forged stolen checks.
"It's like a downward spiral," he said.
Yet he was to be given a second chance when he landed in front of Judge Patricia Marks.
Marks had just started a special court designed to give veterans who commit nonviolent crimes a second chance.
"We're working with someone who has a special quality and that that special quality is that he or she made a commitment to their country, to giving their life," she told Martin.
Stefanovic was facing two years in state prison. Instead, he signed a contract with Judge Marks.
"This isn't a "get-out-of-jail-free card," she said. "It's a 'Who are you? What are you doing? What can we do to provide you with the type of treatment to make you a citizen again?'"
According to the contract, the veteran pleads guilty and promises to go straight. If he stays straight for a year, he gets off with probation. If not, he goes to jail.
"This was the hand that I'd been looking to, to reach out and pull me out of what I was going through," he said. "I truly believe that if I hadn't met Judge Marks, I would either be dead or dying."
Thus far, Stefanovic has gone back to school and stayed away from drugs. He works at a local community college, advising other veterans on the benefits that they are eligible for.
He says that he wants to make sure that what happened to him, doesn't happen to other soldiers returning home from war.