Parental Kidnapping

Well, it depends on if there has been an order prior to a finalization of divorce or if you simply leave the marriage by moving out of state. See the custodial interference statute under kidnapping.  It appears this crime is committed if you have no legal right to take the child.  So, if your spouse somehow gets an order against you (like a temporary or permanent restraining order) to keep you from the child, then you may be committing this offense.

45-5-304. Custodial interference. (1) A person commits the offense of custodial interference if, knowing that the person has no legal right to do so, the person takes, entices, or withholds from lawful custody any child, incompetent person, or other person entrusted by authority of law to the custody of another person or institution.
     (2) A person convicted of the offense of custodial interference shall be imprisoned in the state prison for any term not to exceed 10 years or be fined an amount not to exceed $50,000, or both.
     (3) With respect to the first alleged commission of the offense only, a person who has not left the state does not commit an offense under this section if the person voluntarily returns the child, incompetent person, or other person to lawful custody before arraignment. With respect to the first alleged commission of the offense only, a person who has left the state does not commit an offense under this section if the person voluntarily returns the child, incompetent person, or other person to lawful custody before arrest.

If there is no court order in effect, than you you can take your children out-of-state.  However, your husband can go to court and obtain an order which will require you to return to the state.  If at that point you don't return or return but again leave with the children, you can be charged with parental kidnapping.

The safest way for you to obtain legal custody of the children is for you to go to court first.  Taking a child from their home to live in another state without a court order is not a good idea; either now or in the long run, insofar as a custody battle is concerned.  What you want to do is get a temporary order from the court on custody and visitation.  It will be temporary because a final decree will be issued upon divorce.  The court will consider the bests interests of the children in making its determination.  The court will look at the age of your child, the relationship of the parents and the child, the present living situation of the child, etc. 

Note:  You could file for custody once you re-establish residency in your new state but that will take time.  In the meantime, your husband could file and at that point you would be required at to return back there.

Right now, you need to consult with an attorney in your current state (even if you later decide to file in in your new state).