If you were married as of December 31, 2018, and your Dad filed your 2018 tax return using "Single" as your filing status, then you'll need to file an amended 2018 return (IRS Form 1040X) on which you change your filing status to either Married Filing Joint or Married Filing Separately (the choice would be up to you and your spouse).
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
