I took the following information directly from Washington State Law. I hope that some of it brings you comfort and all of it helps to reassure you that you are doing the right thing.
If you click on the blue underlined stuff it will take you to that website. There is a lot of information and it can quickly become information overload with all of the legal jargon.
DISSOLUTION PROCEEDINGS — LEGAL SEPARATION: This is the chapter that contains all of the information you need to know about what it is and how the courts determine things like child placement, alimony and child support.
POLICY: The state recognizes the fundamental importance of the parent-child relationship to the welfare of the child, and that the relationship between the child and each parent should be fostered unless inconsistent with the child's best interests. Residential time and financial support are equally important components of parenting arrangements. The best interests of the child are served by a parenting arrangement that best maintains a child's emotional growth, health and stability, and physical care. Further, the best interest of the child is ordinarily served when the existing pattern of interaction between a parent and child is altered only to the extent necessitated by the changed relationship of the parents or as required to protect the child from physical, mental, or emotional harm.
RESIDENTIAL PROVISIONS: The court shall make residential provisions for each child which encourage each parent to maintain a loving, stable, and nurturing relationship with the child, consistent with the child's developmental level and the family's social and economic circumstances.
…the court shall consider the following factors:
(i) The relative strength, nature, and stability of the child's relationship with each parent;
(iii) Each parent's past and potential for future performance of parenting functions as defined in *RCW 26.09.004(3), including whether a parent has taken greater responsibility for performing parenting functions relating to the daily needs of the child;
(iv) The emotional needs and developmental level of the child;
Factor (i) shall be given the greatest weight.
DEFINITIONS:
(2) "Parenting functions" means those aspects of the parent-child relationship in which the parent makes decisions and performs functions necessary for the care and growth of the child. Parenting functions include:
(a) Maintaining a loving, stable, consistent, and nurturing relationship with the child;
(b) Attending to the daily needs of the child, such as feeding, clothing, physical care and grooming, supervision, health care, and day care, and engaging in other activities which are appropriate to the developmental level of the child and that are within the social and economic circumstances of the particular family;
(c) Attending to adequate education for the child, including remedial or other education essential to the best interests of the child;
(d) Assisting the child in developing and maintaining appropriate interpersonal relationships;
(e) Exercising appropriate judgment regarding the child's welfare, consistent with the child's developmental level and the family's social and economic circumstances; and
(f) Providing for the financial support of the child.
Payment of costs, attorneys' fees, etc.: The court from time to time after considering the financial resources of both parties may order a party to pay a reasonable amount for the cost to the other party of maintaining or defending any proceeding under this chapter and for reasonable attorneys' fees or other professional fees in connection therewith, including sums for legal services rendered and costs incurred prior to the commencement of the proceeding or enforcement or modification proceedings after entry of judgment.
Disposition of property and liabilities — Factors: the court shall, without regard to misconduct, make such disposition of the property and the liabilities of the parties, either community or separate, as shall appear just and equitable after considering all relevant factors including, but not limited to:
(1) The nature and extent of the community property;
(2) The nature and extent of the separate property;
(3) The duration of the marriage or domestic partnership; and
(4) The economic circumstances of each spouse or domestic partner at the time the division of property is to become effective, including the desirability of awarding the family home or the right to live therein for reasonable periods to a spouse or domestic partner with whom the children reside the majority of the time.