Your filing status is determined by your status as of 12/31 of your tax year. There are options since it seems from your question you were still technically married as of 12/31/21.
There are different situations that are necessary for each option as well as some options that deny you some credits. Since I don't know your whole situation, please see What is my tax filing status (single, married, etc.)? for the best info to help you out.
If you have a dependent child and meet the other requirements you would be able to file as Head of Household.
See this TurboTax support for Head of Household when married - https://ttlc.intuit.com/community/married/help/can-a-married-person-claim-head-of-household-filing-status/00/26366
Your filing status is determined by your status as of 12/31 of your tax year. There are options since it seems from your question you were still technically married as of 12/31/21.
There are different situations that are necessary for each option as well as some options that deny you some credits. Since I don't know your whole situation, please see What is my tax filing status (single, married, etc.)? for the best info to help you out.