Unfortunately, it is not up to your friend. She is the "complaining witness" in this case--that is, while she was the victim, she is not in control of a criminal case, the way she would be if this were a civil case and she had brought the lawsuit. Rather, the "state" (as represented by the DA) is the party bringing a criminal action, so it can go ahead even if your friend wants the charges dropped. Retain an attorney to help you; a good criminal defense attorney may be able to convince the authorities to drop the case, and/or exploint any weaknesses in the case to get it dismissed.