There is no universal standard for how one will be treated in the event one uses lethal force in self defense. In states run by the Barney Franks, Schumers, etc., etc., of the world, you're not going to be treated the same way as if you lived in a state run by the Zell Millers of the world.
Additionally, your specific jurisdiction within a political subdivision will treat you differently than other jurisdictions within the same political subdivison.
Most importantly, why fret about things over which you have absolutely no control? The last thing you want, should you ever need to fire in self-defense, is to have even a glimmer of hesitation or concern about your civil or criminal liability. If you're in a legitimate self-defense situation, YOU'LL KNOW IT!! It won't be like the magical thinking of sophomoric fantasies.
Contrary to information disseminated by those who make a living disseminating information and offering "remedies", there are, in fact, very few civil suits resulting from legitimate cases of self-defense shootings. One can always find an anomalous anecdote of the guy who shot a guy who claimed to be an innocent victim of a sexual solicitation. Maybe the guy was the innocent victim of sexual solicitation! In 99.99999% of the cases, it's going to be pretty evident that Mr. Crackhead A broke into Mr. Honest Homeowner B's home and was killed upon entry. End of case. No suits.
For my anecdote de jour, I'll refer you to a thread started a few weeks ago about the Mercer University law student (Macon, GA) who shot the unarmed intruder who broke into the law student's apartment. Student was watching TV upstairs with g.f. They heard somebody on their front porch. They saw the b.g. They turned their lights on and off, so the b.g. would know they were at home. The bad guy broke in through a large window and, with the burglar alarm blaring, continued to come inside. G.f. was on the phone with 911 while law student had taken a position with his handgun at the bottom of the stairs. Law student makes excellent choice/shot and kills intruder. End of story.
You don't need to put Gerry Spence on retainer. You don't need to buy an umbrella policy. You don't need to spend thousands of dollars on psychotherapy because you're in angst about whether you'll actually have to use the firearm that you own/carry. Just go about your life. If you do have to use a firearm in self-defense, shoot true. Dead men tell no tales. Chances are, you won't get sued. If you do get sued, maybe the prosecutor will hire Messiah Adoodi as an expert witness, and your case will be a breeze.
My fee for all this nearly-Providential advice? $0. Ya gets what ya pay for!