If I was divorced on november 15th, do I still file my taxes joint with my wife or do I have to file single.

[Bsch4477]

If you were not married on December 31 file single  

[Seattlescott]

You file as married filing separately, because you were married for at least one day in 2019. It doesn't matter your marital status was single on December 31. For 2020 tax year you would file as single. 

[KTR33]

But while divorce ends your legal marriage, it doesn’t terminate your or your ex’s obligation to pay your fair share of federal income tax. If your divorce is final by Dec. 31 of the tax-filing year, the IRS will consider you unmarried for the entire year and you won’t be able to file a joint return.

[Bsch4477 · Accepted solution]

From Pub 17 , page 20

Marital Status
In general, your filing status depends on whether you are considered unmarried or mar- ried.
Unmarried persons. You are considered un- married for the whole year if, on the last day of your tax year, you are either:
• Unmarried, or
• Legally separated from your spouse under a divorce or separate maintenance decree. State law governs whether you are married or legally separated under a divorce or separate maintenance decree.
Divorced persons. If you are divorced un- der a final decree by the last day of the year, you are considered unmarried for the whole year.

[Seattlescott]

I was wrong see IRS Publication 504.  You would file as single because not married on Dec 31st

[LindaB1993]

You are considered Single for the entire year if you are divorced on or before  December 31, 2019.

Unmarried persons. You are considered un- married for the whole year if, on the last day of your tax year, you are either:
• Unmarried, or
• Legally separated from your spouse under a divorce or separate maintenance decree. State law governs whether you are married or legally separated under a divorce or separate maintenance decree.
Divorced persons. If you are divorced un- der a final decree by the last day of the year, you are considered unmarried for the whole year.