Did I get your attention?
I am not a proponent of murder but there are laws defining lethal action in self defense.
Each state has it's own version of what are called "Castle Laws".
In some states, Texas in particular, if someone is breaking into your home and you feel that there is a threat to your and/or your family's life you can blow them to hell with a shotgun and it's OK.
You could use any weapon that would do the job if your life is really jeopardized by the armed intruder.
Some other states have a "Duty To Retreat" in some cases built into their laws. In that case the specifies when you would have to retreat from he situation first.
If you violate those laws you could face prosecution for self defense crimes.
All in all I suspect most courts would be sympathetic to you defending yourself if you were the victim of an armed home invasion.
It would be called defense of habitation and could in some cases include your workplace or car.