From what you say, you separated but never obtained any orders concerning custody of the children. That was an error, as you are currently learning.
You raise a number of questions, particularly who moved, as in you are in Hawaii and she is in Utah. That could be of consequence for jurisdiction of the children.
You need to move forward and get a divorce or separation action filed, so that you can proceed to obtain custody orders. And yes, you may have to fly back here to pick up the child if your are successful.
If you want help, I may be able to assist you.
David R. Hartwig
801-486-1715
Answered on May 11th, 2016 at 7:16 AM