My husband moved to another state & bought a house after we were legally separated. Now I want to legally divorce.

Do you have a formal decree of legal separation that was filed with a Washington court in 2005? If yes, then in Washington state, if you obtained a decree of legal separation, then you have a final court order that separates your property. Assuming you have this court order, then it is a final judgment that separated your property in 2005. You can convert a decree of legal separation to a decree of legal dissolution six months after entry of the decree of legal separation, as set out in RCW 26.09.150. Four years have passed since your legal separation, so you should be able to convert it to a decree of dissolution. You will need to file a motion with the court to convert the separation to a divorce. You would not need to include your husband’s new property, assuming he is solely on title and the loan, because it was acquired after the decree of legal separation. I would need to know more facts about your rights to his estate, including whether or not he has a will.