After you file

It's your option.  If the 1099-INT is in your social security number the IRS will look for the full amount on your return.  However you have two options to report the income.

On your return you can enter the 1099-INT and then nominee 50% of it to your ex-husband using the steps below.

1. Search (upper right) > Type 1099int > Jump to ... link > Click the 1099int you need to Edit > Select Edit
2. Put in the full amount of the interest on your form > Continue > Select 'I need to adjust the interest reported on my form.'
3. Continue > enter half of the total interest > Select 'I received all or part of this interest for someone else (I am a nominee)'
4. Continue to finish the entry for this form
5. See image below
6. You can also use Preview My 1040 using the Tax Tools:  
   1. To find Tools: 
      1. Sign into your TurboTax account and open or continue your return. 
      2. Select Tax Tools in the left menu.
      3. You'll find Tools beneath Tax Tools.
      4. Select View Tax Summary
      5. Select Federal Tax Summary (left black panel)
7. Provide information for  your former spouse to enter the balance on their return.