Good afternoon.  It appears that you are a do it yourselfer.  You are asking a question on a professional tax software site for paid professionals.  If you and your ex are going to do your own returns you need to take the time do both do some research.  Here are a couple of links that may help.  Tax software does not make one a competent tax preparer.  

Good luck.

https://www.google.com/search?client=firefox-b-1-d&q=head+of+household+rules

https://turbotax.intuit.com/tax-tips/family/guide-to-filing-taxes-as-head-of-household/L4Nx6DYu9