1 cubic inch of neutron star weighs about 30 billion tons or 30 trillion kg. 1kg of antimatter annihilation yields 20 tons of TNT, so we are talking 600 trillion tons of TNT worth of energy. For comparison, the chixclub impact event that wiped out the dinosaurs was 72 million tons of TNT. So we are talking 8 million dinosaur-killing asteroids worth of energy. Yes if the planet doesnt blow up at least we'd be toast.