darn, Paul. This is terrible news. I know exactly what you're feeling- the loss, the sense of betrayal, and the isolation. I went through it back in November, and I'm still grieving. The sneakiness of it is for me the worst because I was actually asleep when she snuck off. I had no chance to try to change her mind, or work out our circumstances, or even to ask why. She just disappeared for a week. In the end I've decided to cut her entirely out of my life, not even to deal wit hthe divorce (I'll pay financially but it's just easier this way, for me).
Just have some faith, and do the footwork to get your children back. At this point you have GOT to pay attention to the details that will make sure the right thing happens later. Get a lawyer, and be aggressive legally. Don't play nice just because you want the best thing for your kids. The best thing for your kids will be to have both thier parents fully involved in their life. For me the first week's depression was the worst, and I gave her family a lot of the things I should have kept in order to gain rights I both needed and deserved. Don't make the mistake just to be nice or because you feel guilty.
Follow the bouncy ball, dude. Don't let your grief and anger drive you to mistakes you and your children will regret later. And believe it, it will all be all right, if not the same as before!
Good luck
