You can file as Joint if you both agree or Married filing Separate, but if you don't have his info you will have to mail your return. Or you can file Head of Household if you qualify.
You may be able to file as head of household if you meet all the following 3 requirements (A-C). Copied from Pub 501.
A. To claim head of household you have to be unmarried or to be considered unmarried. You are considered unmarried on the last day of the tax year if you meet all the following tests:
1. You file a separate return.
2. You paid more than half the cost of keeping up your home for the tax year.
3. Your spouse did not live in your home during the last 6 months of the year.
4. Your home was the main home of your child, stepchild, or foster child for more than half the year.
5. You must be able to claim an exemption for the child. However you can meet this test if you cannot claim the exemption only because the noncustodial parent can claim the child.
B. You paid more than half the cost of keeping up a home for the year.
C. A "qualifying person" lived with you in the home for more than half the year (except for temporary absences, such as school). However if the "qualifying person" is your dependent parent, he or she does not have to live with you.
See pub 501 page 9 for who qualifies you for HOH
http://www.irs.gov/publications/p17/ch02.html#en_US_2011_publink1000170821
or the pdf……
http://www.irs.gov/pub/irs-pdf/p501.pdf
