Married by law in Texas
Wife is in the process of immigration from Germany
Immigration paperwork is filed, but no SSN or Greencard yet
She lived here all last year, but did not work

Do I file Married Joint, Married Separate, or Single?

Not single status but either MFJ or MFS; you opt to treat your nonresident spouse as a resident and file a joint return, your spouse is required to claim all income, including earnings from outside the U.S., which could increase your tax liability. To file a joint return, you must attach a statement to your tax return explaining your decision. Your nonresident spouse must have an individual taxpayer identification number. If your spouse does not have an ITIN, complete Form W-7 and attach it to your tax return

aslongas you file your return as MFS then your spouse doesn't needto report her incoem in German y and you donot nedto report yourUS income to Germany but yopuneed to rpeort your US source income only to IRS