20 years seems kind of harsh but I do agree with what she did was wrong.
She never should have returned to the house with the gun unless she thought her children were in danger.
If she stayed in the garage and her husband followed her into the garage and attempted to psychically harm her, then she would be in the right for firing the warning shot. Correct?
Lastly, she should never have fired the warning shot in her husbands direction while he was by the kids. This puts her kids in danger, if she felt the need to she should have shot the ground or ceiling or out a window, depending on the layout of their home.
On a side note. She should have left this guy ALONG time ago AND got a restraining order. Only a poc would ever beat a girl. I just don't understand some women lol