His wife, sister-in-law and her children were able to escape the van.
Macwan, a business lecturer from Auckland, said: "I can understand her struggle. When I heard about the tragedy, I immediately thought of my own son.
"I blamed myself for a long time afterwards. In my own mind I thought other people were blaming me, too. It was a daily torture I thought would never end."
After the accident, Macwan was discharged without conviction at Manukau District Court after being charged with careless driving causing death.
"People thought how terrible it must have been dealing with the police as well as all the grief. But at the time I was in so much pain that any potential punishment seemed nothing in comparison."
Macwan said a turning point came with the birth of his daughter Aashka, who turned 3 last month.
"Aarush was our only child when he died and family relationships were really tested afterwards," he explained.
"You keep asking yourself how could this have happened and wondering if you are a bad parent.
"Our daughter has given us focus. It helps when you have someone else to give your love to."
Macwan added: "It is easy to say and difficult to do but you have to forgive yourself. I eventually found some peace again but I had to find someone close I could connect and share my feelings with, someone who would not be judgmental.
"The baby's mother will eventually work her way through this."
