Unfortunately, the charges are technically brought not by her by the local District Attorney. Even if she changes her mind, they can press on with the case. Often, spouse abuse victims relent under pressure and/or change of mind, but the DA will not dismiss the case, calling her as an involuntary victim if necessary.
Your best bet is to get a good criminal attorney ASAP.
A order for emergency protect is a temporary restraining that order lasts 61 days & prevents one from going to the other's home or place of business, or communicating directly or through another in a threatening or harassing manner. It is generally signed by the judge in front of whom the criminal case is pending. It can be altered by the judge to allow the accused to return home IF the complainant witness wants it. (I have had it done even in spite of the prosecutor's opposition.) This type of order requires no notice to the accused and it is done on a regular basis in cases where the is family violence alleged.
A true protective order, obtained after notice to the accused, lasts 2 years if obtained. The accused is entitled to a hearing on it. Moreover, it prevents ANY contact with the complainant.
As far as dropping criminal charges, your wife can file an affidavit of non-prosecution and tell the prosecutors she does not want to proceed. However, it is up to the State whether or not to proceed, even if you wife does not want to do so.