What do you mean you filed "single?" If you were legally married at the end of 2018 your filing choices were to file as married filing jointly or married filing separately. If you filed "Single" you made a huge mistake. You need to seek the assistance of a paid tax professional to sort out the mistake you made. Amending using TurboTax is a really bad idea.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
