Has the 'Deadly Force Triangle' been met? Sounds like it has. The laws of the State your in are clear enough but we all know how things can get twisted around when presented to a jury. Bottom line, is it a life or death situation/scenario? Yep.
Regardless of what action you (or I) take, the first order of business is skinning leather, staying outta said BG's line of sight if possiable, and mentally readying yourself for a fight.