If you will be filing joint, then you need an ITIN for your spouse since I'm assuming they do not qualify for an SSN. Additionally, you must both claim/report all worldwide income from all sources on the joint tax return. To get an ITIN you'll need to file form W-7 with the IRS. Get the form at https://www.irs.gov/pub/irs-pdf/fw7.pdf Fill out the form and mail it with your 2018 tax return. Note that you will have no choice but to print, sign and mail the return this year.
Otherwise, you file Married Filing Separate and you can NOT claim your spouse as a dependent. Note that if you file separate, you will still have to print, sign and mail the return since it would still require the SSN/ITIN of your spouse.
