If she is convicted of a felony, she can never become a peace officer.
Even if she is convicted of a domestic violence misdemeanor, she can never become a peace officer. Under federal law, a person convicted of a domestic violence misdemeanor can never own or possess a firearm... and without the ability to carry a gun, she cannot become a deputy sheriff.
You are not the ones who will "win" or lose this case. The District Attorney files criminal charges on behalf of the People of the State of California -- not individuals -- because crimes are considered offenses against society, not just the alleged victims.