In order to file head of household you have to be (1) considered unmarried, (2) you paid for more than half of cost of keeping up the home, and (3) a "qualifying" person lived with you for more than half of the year. It looks like you would qualify for head of household status. It looks like you qualify if your separation is done by legal decree, or lived apart for 6 months.
Obviously you haven't retained my services, I am just directing you in the right direction. You should seek the help of a qualified accountant.