My husband is not a US citizen and has no status in the US. How does this fit into the filing form? Last year I was considered head of household.

To get the Head of Household filing status and receive the personal exemption for the nonresident alien spouse using the online editions, you will have to actually lie to the software.

If you are a US citizen and your spouse does not have a Social Security number or an ITIN and you are not applying for an ITIN with the tax return then you can only file your tax return as Married Filing Separately.  Where asked to enter the spouse's Social Security number enter 999-88-9999.  You can only print and mail your tax return, it cannot be e-filed.  When you print the tax return erase the Social Security number for your spouse and manually enter NRA for non-resident alien.

In the Personal Info section for the Fling Status, where it now shows that you are Married Filing Separately, click on Edit.  The next screen 'Let's confirm your marital status' click Continue.  The following screen 'Let's see if these apply' is where you lie to the software by checking the box labeled 'I didn't live with (spouse name) at any time between July 1, 2016, and December 31, 2016.'  and clicking Continue.  The next screen should already have the boxes checked so you claim your spouse's personal exemption, if not check all three boxes and Continue.  There will be several other information screens and then you will land on the screen Did you pay more than half the cost to keep up your home in 2016? check Yes and Continue.  The next screen should show you your filing status as Head of Household.