That's second degree murder charge doesn't stand a chance in NH.

I definitely don't think it's that cut-and-dry.

NH law says that to use deadly force, the threat you're defending from has to be deadly.

If a woman punched a man in the face and the man whipped out a gun and emptied 8 shots into her head, I think there is an extremely high chance the self-defense law would not apply. Yes this is two men, but one is a foot shorter than the other and 50-100 lbs lighter. The punch barely broke his stance. There's definitely an argument that could be made about if the threat was deadly.

NH law also says you can't be the initial aggressor, and if you are you have to make an obvious attempt to retreat. It also says you have to have not agreed to a "combat". If the guy with the gun said something along the lines of "Meet me outside, I'll kick your ass", the self defense law may no longer apply.