Single father, filing as head of the house or married

Hi,

In May 31st, 2020, my wife left me and our 6 month old son and went back to her country. I took care of him by myself. I filed for divorce at the end of  July 2020, but I did not get a case number until October 21st 2020, and just now are half way with divorce papers . I'm wondering if I should file as married again, or head of the house? We also, both got stimulus checks in May 2020, $1200 each. In 2019 we filed as married with one dependent.