How can I file back and not have to travel back?

If your spouse is still in WA you can file here. By filing here you are putting yourself under the jurisdiction of the State of WA. If your spouse is not here, the question would be where he or she is since the court needs to have jurisdiction over the other party. If there is real property in WA (land or houses) you can also file here on that basis and because you both lived here during the marriage.