An impulsive act of rage has led to a 10-year prison sentence for an arsonist whose reckless behavior resulted in the tragic death of a teenager attending a sleepover.

The incident stemmed from a heated neighborhood dispute in Waterloo, where Gregory John Walker, fueled by anger, hurled a Molotov cocktail into a home’s kitchen.

In the ensuing chaos, a young victim was forced to leap from a window to escape the blaze, sustaining severe burns over 65 percent of his body.

The court heard that the 58-year-old Walker exhibited a “callous disregard for the enormity of what occurred” in the fire’s aftermath.

When confronted by a neighbor who accused him of starting the fire, Walker, then 30, brazenly responded, “If you think that was a big fire, wait until you see my next one.”

However, Justice Dhanji noted that Walker has since expressed remorse for his actions.

In 2014, as police tried to mount a case against him, he told a witness he “wouldn’t have gone through with it” if he knew children were inside the home.

But evidence showed the former boxer had effectively turned his life around since his deadly actions in 1998, even establishing a not-for-profit for young people.

“There is an element of him attempting to make good on his past wrongs,” Justice Dhanji said.

That was despite Arthur’s family’s obvious desire and lengthy wait for answers.

“While the ledger cannot be squared by the good done by the offender in recent times, that contribution must be taken into account and given weight,” Justice Dhanji said.

With time served, Walker will be eligible for parole in February 2029.

Arthur’s mother Julie Szabo, who ensured the public never forgot her son during repeated media appearances seeking answers, was surrounded by loved ones as the sentence was delivered.

She previously detailed the heavy guilt she has carried since allowing Arthur to have his first sleepover with friends.

“It was going to be the first night he had not slept under the same roof as me,” Szabo wrote in a statement earlier read out in court.

“I said ‘yes’ … I think about that decision a lot.

“I gave him the biggest hug, we both said we loved each other, I didn’t know at the time it would be one of our last hugs.”

“No sentence I impose can right the wrong that has been done,” he said.

Justice Dhanji also took into account a charge of maliciously inflicting grievous bodily harm that Walker committed when he punched a neighbour and bit off part of his ear in April 1998.