I recommend this book.
https://www.amazon.com/Killing-Psychological-Cost-Learning-Society/dp/0316040932
I sure as hell hope they have insurance to cover their legal costs. Also, this probably will result in bad consequences for the couple. The standard an armed civilian is higher than for a uniformed law enforcement officer. (At least it seems that way.)
Yup. Sadly, they will pay a heavy price for this.
Personally, I favor extremely liberal laws on self-defense and trespassing. If I were on a jury, I would give enormous weight to the homeowner on his own property. Very unlikely I would vote to convict under any circumstances.
My husband taught self-defense - for women in particular.
He said the most difficult thing for women is to pull the trigger when they need to pull the trigger - they tend to hold back - and if they do, the assailant is going to take the gun away from them, as in this case. Stopping that hesitation is almost impossible to teach.
I would have pulled the trigger, no doubt, no hesitation.
Protecting my children - with deadly force- is always foremost in my mind. I’d do the same for my animals.