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.