Mr O'Brien had left his wife Bianka and baby Jude asleep in their Rozelle apartment as he left for work early in the morning of September 4, 2014. He returned just over an hour later to find his family – and much where they lived – gone.

Their Darling Street apartment, that of their neighbours and the shopfronts below, had been deliberately blown up by store owner Adeel Khan in an attempted insurance scam.

Three days after the explosion, Mr O'Brien drove to Surry Hills to write a statement for the media in tribute to his much-loved wife and child.

He sat and worked on it with police media advisor Michelle Minehan, who happened to be working that Sunday and was a friend of Mr O'Brien from his old gym

Little did he know at the time that he was taking a small, but significant step to help rebuild his life.

"In a lot of ways she's saved my life," said Mr O'Brien this week, speaking publicly for the first time since the September 2014 fire.

"I was fearing that I would never actually be normal again, that's the God honest truth. I thought I'd have a mental break down, that I'd be locked up, I wouldn't be able to work anymore, I'd be a mess.

"But Michelle changed all that, she picked me up when I was at my lowest. She made me feel like everything was going to be OK.

"That beautiful person changed my whole outlook on life."

Through her role with the police, Ms Minehan was aware of the magnitude of the tragedy Mr O'Brien was dealing with and soon became someone he could talk to about it, and other things in life.

Over time their dealings and discussions moved from the professional to personal.

Now they are in a relationship, living together, and are expecting their first child in eight weeks.

Mr O'Brien said the first few weeks after the Rozelle explosion were a blur: he arranged the funeral, dealt with the police investigation and the start of the court process after Khan was charged with their murders.

Khan killed Ms O'Brien, Jude and their neighbour Chris Noble when he blew up his failing Rozelle convenience store to claim $225,000 in insurance money.

The 46-year-old set up an elaborate network of 10 petrol containers throughout the store – connected by strips of petrol-soaked material – then set it all on fire.

The fire flattened the store and the units above where Mr Noble lived with two mates in an apartment with the O'Briens next door.

Mr Noble's body was found later that night. Ms O'Brien and baby Jude were discovered by police more than 24 hours later as they had been for all of their short lives together: side by side.

Three young, beautiful lives were taken by an act of greed that Khan still refuses to take responsibility for.

Mr O'Brien was left with only the clothes he was wearing that Thursday morning and a couple of Jude's rubber duckies salvaged by a firefighter among the rubble.

"I was staying in hotels, in places that were busy, like the CBD, where something was going on and there a constant distraction," he said.

After two months of hotels and crashing on friend's couches, he started to get some normality back in his life: he returned to his job as a mechanical electrician, started going back to the gym and spending time with friends.

An "eternal optimist", Mr O'Brien said it was important he did not dwell too long in the past.

"I just went to work one morning and their lives were gone. It was so sudden. After the shock I was almost consumed with living in the past saying: 'I should have done this or said that.' It was such an easy thing to do, but with help from friends, family and especially Michelle, who at times pretty much had to carry me, I made my way through. Life is great and I have so much to look forward to.

"You've got two ways of doing it, you can freeze in the moment or move on, that's your two choices."

In the first half of 2015, Mr O'Brien took time off to travel overseas and, again through coincidence, found himself in New York at the same time as Ms Minehan.

They hung out and their friendship grew. When she returned to Sydney later that year, that friendship developed into a relationship.

"From the very start, he has never wanted anyone to feel sorry for him," Ms Minehan said.

"At first I thought it was just a front but he's shown time and time again that's the person he is. He has the most positive attitude and he puts everyone else first.

"He will say to people that I saved him but I see it in a completely different way. He's changed my life. I used to stress about the littlest details and he put everything in perspective for me. This man can be so positive with what he's been through and I'm worrying about something so minor. He's done more for me than I've done for him."

Initially Mr O'Brien tried to keep much of his anguish to himself, not wanting to burden Ms Minehan with what he was going through.

"He's had hard times," Ms Minehan said. "Over time I tried to get it out of him and, once he started talking about Jude and his wife, he was a changed person. Now going to the baby stores, and I know nothing about it all, and he's talking about Jude every single day now in relation to our baby. He'll say 'we have to buy that, Jude loved that'.

"It's been a positive thing. I was a bit worried about how it might be, if it might bring back memories but it seems to have not done that. It has done the opposite."

There were, however, tough times during Khan's trial this year. Mr O'Brien insisted he sit through the entire three weeks of evidence.

"He became consumed by the court case," Ms Minehan said. "He wanted to look at all the evidence. He wanted the coroner's report. It was very hard to watch him read it but he said from the beginning he needed to know what had happened and that, had he been there, he couldn't have saved them.

"That's how he processes it all."

Khan was convicted of the murder of Mr Noble and the manslaughter of Ms O'Brien and Jude in June. In sentencing Khan to 40 years' prison, with a 30-year non-parole period on Friday, Justice Elizabeth Fullerton said his setting and lighting of a petrol-fuelled fire was "offending of the most serious kind".

Mr O'Brien said the lengthy sentence had not given him any closure, that's something he is working on achieving himself.

"The damage is done, you can hate all you want, you can give him life but it doesn't change anything.

"You always want to see guys like that punished, you want the longest sentence possible to stop the next guy who is thinking about doing that but I don't get any personal satisfaction out of that.

"You are the only one who can move on. If you start relying on someone else, it is destined to fail."

smh.com.au