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In order to claim mortgage interest and property taxes, one must be liable for the debt, actually pay the expense, and be on title to the property. If the loan is solely in your name and you live in a non-community property state, you would be entitled to the full deduction barring a court order stating otherwise. I would suggest you file you tax return correctly. If the IRS follows up with inquires, you will have the documentation to back up your deduction, your ex-wife would not.
Since the mortgage is a joint account, you would have to show you paid all the mortgage interest payments with no consideration form her. If you can do that, the correct way to file would be for you to claim the entire deduction on your return. She would then have to prove to the IRS she paid for the deduction she claimed when questioned by the IRS.