Some other considerations:
If he is ineligible for HOH as per Zbucklyo's explanation, and he files MFS and itemizes, then you must itemize too - even if the standard deduction would be more advantageous to you. This is one of the disadvantages of MFS. With MFS, if one spouse itemizes, the other must itemize too.
MFS is even more complicated if you live in a community property state.
It may be more advantageous to you to file MFJ with a Form 8379 Injured Spouse allocation. This would preserve your portion of a joint refund while preserving the advantages of filing MFJ.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
