I got some questions:
- Is the
marriage still legal in the home country?
- Can she get legally divorced in the home country?
If the F1 application stated that she was single and not married because the marriage was not legally conducted, then she is still single! You got to figure out the legal situation in the home country.
If she is not legally married, then she can do whatever she want, in my opinion. Being on an F-1 visa makes it easy to change status, so that is a good idea while she is still in the U.S. However, GET A LAWYER to deal with it. Cough up the 2-3K he or she will charge. You must do this.
GOOD LUCK!