No, unless the crime is the improper use of the gun in the first place. (Which is the case here--the conditions of self-defense aren't met, thus the shot is illegal.)
Firing a gun at people is a crime unless you're doing it in self defense.
There is no proof she actually fired the gun at someone, where there is ample reason to assume she would with to warn her violent husband.
Further, an important fact is the onus of proof was placed on the defendant not the prosecution. This is why there is a retrial, though really show should have been released. However the prosecutor has spent a lot of time giving press conferences and even trying to influence lawmakers who were debating an amendment to this bill.
Firing a gun near someone is a crime unless you're doing it in self defense.
And of course she has the burden here, although not to the beyond-a-reasonable-doubt standard. You claim self defense, you have to present evidence of self defense.