Dear Customer (name blocked for privacy),
It would be very difficult in this case to prove fraud without implicating yourself to some degree.
At this stage of things you have to look at the evidence represented on the Permanent Residence application forms and the supporting evidence. If any of her part is forged, or false, you can report this to the ICE and ask the to look at this as fraud. If the green card application was falsified in any way, it is a crime and the she would be determined to be inadmissable,and her green card withdrawn, and she would be ordered to a deportation hearing in court. However this is a long process, and not a quick fix.
In the mean time, even if she were an illegal alien, she would still be able to file charges of domestic abuse in court and file restraining orders.
The best you could hope for is leverage. If she were to come under investigation by the immigration inforcement, then she may withdraw her complaint and protective orders. However this is not a gaurantee.
I read your other questions. One thing that needs to be made clear to you is:
1. In order for her charges to be sustained in court, there has to be real evidence, not just hearsay. If you have a good attorney and are innocent, you should not have much to worry about. However, as you know there are no gaurantees. We cannot predict judicial outcomes.
2. Even if innocent, with domestic violence, authorities act first and ask questions later. so, a unbased accusation can result in an arrest and charges, only to fall away in court.
Finally, even though your wife may be leveraged to drop her case; the court may decide to leave the protective orders in place, even if your spouse is asking to have it removed.
YOUR PAYMENT AND BONUS IF ANY MAY BE TAX DEDUCTIBLE

Edward M. Johnson