Since you have already filed and your return has been accepted, you will need to complete and mail in Form 8379.  This form can be filed separately, so you will not have to Amend your original return. 

Please follow these instructions in order to complete Form 8379 after you have already filed in Turbotax online and mail it in as soon as possible:

• Login to your TurboTax Account 
• Select "Tax Home" from the left side of your screen
• Select "Show" next to your "Returns & Documents"
• Choose the year you want to add the Form 8379, then select Amend (change) return. [Note, you are not really Amending your return, this is just how you get to the form in order to fill it out.]
• Click "Search" in the upper right corner, then type "Injured Spouse" in the Search Box 
• When the results populate, click the "Jump to Link"
• Click "Yes" where it asks "Do you want to claim innocent or injured spouse relief?"
• From here TurboTax will walk you through preparing an Injured Spouse Form 8379
• Once finished, you will need to print, sign and mail your Form 8379

If you have any issues, please comment below so that I can assist you further.