Not knowing her location is your biggest hurdle. In order to divorce, you have to legally serve her with the Petition. If you can't prove that she has notice of the proceedings, no divorce. it would be best to hire counsel because there are alternatives. If you don't you could end up spending a lot more more money going around in circles trying to comply with the court rules as to process of service.
Please note that THESE COMMENTS ARE NOT INTENDED AS LEGAL ADVICE and are for informational purposes only. This response is not intended to create any attorney-client relationship and is only based on the limited facts given. The response might change should additional facts be learned and should not be relied on as legal advice. It is recommended that you consult with an attorney who can properly assess the situation, as well as all pertinent facts, prior to taking any action based on the foregoing statements
It is feasible, though often quite frustrating, for people to file a "do-it-yourself divorce" under circumstances such as you describe. If you don't have funds to retain or consult with an attorney, then you have answered your own question. You can try to obtain free or limited fee legal help through CLEAR, the KCBA Lawyer Referral Service or Neighborhood Clinics or the WSBA Moderate Means Program. You may also find helpful resourcesat: http://www.washingtonlawhelp.org/ and through the Family Court website: http://www.kingcounty.gov/courts/FamilyCourt.aspx. The forms you need can be obtained through: http://www.courts.wa.gov/forms/. Good luck.
Legal information provided in this answer does not constitute legal advice nor does it establish an attorney-client relationship. The information is general and only accounts for the information you provided in your question. Please call me if you want legal advice pertinent to the details of your situation.
No, you do not necessarily need an attorney, but I would nevertheless advise you to thoroughly research the process and make sure you feel comfortable going it alone. Generally speaking, it is always to your advantage to be represented in a divorce process, especially when there are minor children involved. To get you started in your research, I would advise that you peruse the Washington Law Help website.
You indicate that you have little information on how to find your spouse -- if your attempts to locate him/her are unsuccessful, then I advise you to consult RCW 4.28.100 for information on proper service of summons through "publication." If your spouse never answers, then it might be relatively straightforward. However, should you locate your spouse, or if he/she responds to the publication, then you have to be concerned about the possibility that (s)he could challenge you for custody; if that happens, then I would strongly advise you to hire an attorney.
The best way to determine an attorney's value in your case is to first conduct your research and then determine whether you're comfortable going it alone. When children are part of the equation, the money you spend on an attorney is almost always going to be a solid investment.
Glad to help further if I can.
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