I'm predicting this will come out:
No adultery or abuse by her husband.
She's had bouts of depression since her toddler was born.
Because of recent stressers, she just totally lost it.
Seeing I have had PPD and I wanted to kill my DH a few times myself I'd say that was the cause. She was depressed and he was driving her nuts. There was a gun in the house and when they were arguing she went and got it and out of anger shot and killed him. However, she is being charged with 1st degree murder and 1st degree mean she planned it, it wasn't something she just did out of the blue.
So maybe insurance money and she was falling in love with some guy she met on the internet but knew she could never just leave her husband.
WHO KNOWS!