At the risk of being blasted again by someone, in part I understand where you are coming from, however, I absolutely can paint a picture of a guy killing in a blind rage, for me it is the "intentionality" I can't tally it with albeit perhaps I use the word incorrectly. I believe OP could have shot at the door in a rage, a blind rage, a rage that gave him no time to reason or to think of the consequences which for me is constitutes without "intention". Otherwise what motive? What gain by killing her, to the contrary if OP is an abuser, as it appears he likely is, then by killing her he extinguishes the object of his control which as an abuser he needs to be able to thrive.
For the record, none of what I have written constitutes an excuse for OP, nor a mitigation if it is indeed what happened and imo murder would most certainly not be over charged as some opine. But that is just my opinion.