Again, this is a horrible situation for a mother. I can completely understand your anger at the system not protecting your children. How these kinds of abuses can be tolerated is beyond me, but I see the results of it in my counseling practice all the time.
It sounds like you're well into the legal system and that monolith has a speed all it's own. You can only do what you're doing now and keep pressing the issue. Don't for a minute let your guard down. Gather as much evidence as you can and keep documenting. When staff changes at the courthouse, you can lose information, so always keep your own copy of everything.
Get support for yourself. Read some of the blogs on this site:
You'll hear women like yourself deal with these same issues. Abusive men will use their children to get control, and control is the name of the game here. What is happening to you is abuse.
Talk and vent and share with people. Don't hold his shame for him. Make the best life that you can with your kids, knowing that this time in their lives will not be totally dominated by him. They're with you right now_keep making that count without letting him wear you down.
You're not crazy, and you're not making this stuff up. Men do this all the time to women and yes, they often get away with it. Fight the good fight for your kids and don't give up. It sounds like you've done so much already. You're doing the right thing...just keep it up!
I admire your courage.