I just came across this, it sounds like the person may not have understood that in 2019 you and your husband could have separate filing statuses at the State level.
Your filing would have depended on if you were a statutory resident of NYS in 2019- did you have a permanent place of abode in NYS and spend > 183 days here? If the answer is yes, you need to file a married filing separate full-year IT-201 return, even though you moved to London before the end of the year.
If you are not a statutory resident, you can file a married filing joint IT-203 nonresident return. In the NYS column, you prorate all of the income you earned, or otherwise accrued to you, while you were a resident. You exclude all of your husband's non-NY source income reported in the federal column.
You would do the same on form IT-360.1 if you were a part-year City resident. Attach a statement with your return that breaks down your income and your husbands income, as if you were filing separate tax returns.
Domicile changes to a foreign country are especially difficult to prove. You have some good facts. You can seek coverage under the 548-day rule in any given year you are concerned about an audit risk. More about that here: https://www.hodgsonruss.com/media/publication/[social security number removed]%20The%20Nuts%20and%20...
Best of luck and enjoy London.
Kristine L. Bly, EA Private Client Services / Residency / Tax Controversy
Partner, Cohen & Company
