Andrew Partington drunkenly cut two gas pipes in his house because his girlfriend had left him and taken their children, the court heard.
He sent a series of Blackberry instant messages to partner Ms Williams on the night before the explosion.
In one he wrote: "Told you next time you leave, house goes up with me. You left your kids with no dad no home. Goodbye. Boom. Gas pipes cut. Already filled up. Boom."
He let his house fill with gas overnight, but said he woke up and cut the gas supply and opened windows.
Partington then lit a cigarette, with devastating consequences.
More top news
The PM promises to double to 200,000 the number of homes built under an existing scheme aimed at easing Britain's housing shortage.
The Met Office has weather warnings in place for snow and ice until 10am in the north and west.
The plan, which would effectively strip banks of the benefit of recent corporation tax cuts, forms part of the party's election manifesto.