This is premeditated. One does not SNAP and go and get a shotgun and blow somebody away while they are sleeping. When a person SNAPS, there are no thought processes involved. What she did was calmly and cooly get the shotgun, walk to the bedroom, enter the bedroom, aim the weapon, and pull the trigger.
This will be a whitewash because of abuse claims. Can anyone say "Burning Bed"?
Where were the kids while she was doing this? Were they in the house, or were they in the car. If they were in the car, waiting for her, that's further evidence of premeditation.
If verbal abuse were reason to murder, I know an Online chocolat seller that would have met her demise years ago.