The guy you knew from HS was totally in the wrong and deserved to be charged. The guy with the gun was just protecting himself. And since his car is an extension of his domicile in most states, it would be no different than if HS guy broke through the front door of his house with a bat.
Just sayin'.
If the OP were to protect herself and her family in her domicile with an object that is legal for her to own, she most likely won't be charged either.
Can not a vehicle also be considered a weapon? And the other party struck first?