file as Head of Household if you have a qualifying dependent.  See the following FAQ:  https://ttlc.intuit.com/replies/4206137

If after reading that FAQ you determine that you qualify, that is probably your most advantageous filing status.  (Note:  you have to have been apart from your ex since at least July 1 or before to qualify).  If you do not qualify, then your status will be Married Filing Joint (if you can reconcile enough to file together), or Married Filing Separately, which, although it is the least advantageous status, may be the only option available to you.