I'm sorry to hear that things are all over the place for you at this time.
Stop moving. Be still. Take a deep breath. Hold it. Slowly exhale.
Do it again...
And again...
And again.
First things first..
This is about you.. not him, not her. He's taking up way too much prime real estate in your brain. Shoo those thoughts of him out and focus on what is important.
You.
Your kids.
What the former man of your dreams, father of your children, divorced spouse is doing is NONE of your business. His ultimate choices created a new and far different life for you and your children than you ever imagined
As much as you may blame her for cajoling him away from his marriage and family, him for 'succumbing', he's a grown man who is responsible for the decisions he's made. By choosing to move 700 miles from him, you've placed a physical barrier that limits any and all interactions he has with his children.
They want nothing to do with her, or him if he is with her, which they have that option.
How much leeway do they have? What does it mean?
Even though you're angry, hurt and feel betrayed all kids need both parents. The fact he wants to be involved in their lives is a VERY good thing. And the kids know how much this hurts you and may feel a need to protect you when it comes to their dad.
My ex did more or less the same thing.. said he was miserable, moved out to a place no one could visit or know the address (our children included) which ultimately turned out to be her condo. With his rapid departure came divorce papers. She-bam. However, he is a 'dinner date' dad, giving about one hour every week or so to the kids at a local diner. He immediately married the woman he 'dated' during our marriage once the divorce was final.
My kids have someone they can talk to (within a time period).. a father, but no longer a dad.. no longer that special person in their lives they can hang out with, have casual time with, shoot the breeze, be a part of his/their life on an ongoing basis.
Divorce sucks for all kids. But your children have a father who wants to be with them, who's willing to let them make up their minds.. just as he's made up his with his choices. Let them choose.. and the choice should happen over time. You cannot control your former spouse's actions, nor should you. You can be the rock, the 'safe' place where your kids can turn for support.. where they can be children, be listened to.
Wish him blessings when you're pissed.. it helps dissipate the anger and promotes forgiveness (a gift you give to yourself.)