there were 911 contacts about the couple threatening minors on the property, etc...Yup. Definitely situations where you need to defend yourself. And while someone's history isn't a reason for them to be shot, it does suggest something else may have happened. As an example, based on that history, and having heard of similar situations occur: She got high on something that was not what she thought, got aggressive or hallucinated. Then went to either attack the kid (that the CPS cases are about), or even worse, got angry with the kid and went to attack it. If he's in fear for his own life, the gun is a fair option. If it's a kid and he's not close enough to stop her, the gun is pretty much the only option.
Obviously I don't know the story-all I know is what you posted. But this is an entirely possible situation, and certain outlets would not release (or hide halfway through the story) all those details.
It would make for a script nobody in Hollywood would buy as too contrived.
It might end up on Lifetime though.