Go to
www.annualcreditreport.com. From there you should be able to view each of her three major credit reports for free, assuming that you haven't viewed them for free within the last year. If there's crazy stuff on there you didn't authorize--like a credit card she doesn't actually have, or a car loan for a car she didn't buy--you can use the information from there to begin the process of canceling that account and prove it wasn't her. You can also put a "fraud alert" on each of the credit reports, which will make it much harder for any loan/credit card to be taken out under her social security number for awhile.