MADD has spent the last 20 years pushing for tougher DUI laws, and they aren't finished. If they had their way, the laws would be much tougher than they are now.
The way to minimize your risk is to never take any DUI test: no field tests, no breath and no blood.
The state took over the case the moment your fiancée called the police.
In a criminal case, the charges do not belong to the victim, so the victim can't "drop" the charges any more than the victim could increase the charges. Criminal charges are brought by a District Attorney or Solicitor on behalf of the victim, who is just a witness in the case like anyone else. Victims can communicate with the prosecutor to express their disinterest in seeing the case prosecuted, but the ultimate...
Don't overlook that you can also attack the roadblock itself. I currently have a roadblock case before the Supreme Court of Georgia and know the law pretty well. A DUI from a roadblock is better for you than a regular DUI where you get stopped on the highway.
There are several ways for a lawyer to keep a client driving if the client gets the lawyer involved immediately. I would say that I and most of the DUI lawyers on here keep our clients driving more often than not.