You can file Form I-130 (Petition for Alien Relative) to start the process of bringing your spouse to the U.S. Since you're a permanent resident, your spouse would fall under the F2A visa category.

Wait times for F2A petitions vary, but they’ve recently been shorter than other family categories. After I-130 approval, your spouse will go through consular processing at the U.S. embassy in Sri Lanka.

Once you become a U.S. citizen, the petition can be upgraded to the Immediate Relative category, which usually processes faster and has no annual cap. You don’t need to refile—just notify USCIS after naturalization.