So---assuming you are filing married filing separately? If so, you both have to follow the rules. If one spouse itemized, the other must also itemize. If one used standard deduction, the other must use standard deduction. And if you itemize----there is no "double dipping" allowed. You cannot both take 100% of a deduction.
It is not in her interest to lie about it, since it could result in a problem for her as well as for you. But the IRS is not going to tell you how she filed. If she will not tell you whether she used itemized or standard deduction, you might need to involve your attorney--or just take your chances on how you file your own return.