Hi, R. I have been away, and am just now reading this thread. I, too, have joint custody (I have primary) with an idiot, who (hard to believe) is just like your ex. I am always surprised at how many of them there are....
I know the catch 22 you are in: the one thing (or three!) in your life that you would give your life for....is your children. This is also the one thing that your awful ex and you share...and the one thing that he will use to punish you with. Why? Because you care about your kids. If my ex fell off the earth, the planet would be a much better place....and I wouldn't care a bit, or even notice, because I would no longer have any thing to do with him. But what are we to do? Not care for our children? Rather unlikely!!!
My ex Nidiot takes me to court repeatedly. I wanted to move two years ago (we have been divorced 9 years), and he fought me, even though he travels extensively throughout the world, leaving sometimes for as long as 6 to 8 months (visiting every few a bit). I lost the case to take my kids with me, and lost the appeal as well (or half of it, they reversed part). Anyway, he now has taken me back to court to reduce his child support. He LIVES for negative interaction with me. He has not let go of me one bit. He is remarried, and why his wife puts up with his obsession with bullying me is beyond me (and I don't really care).
Unfortunately, I don't have any Psych testing on him. Oh well. My kids are teenagers, and mostly get what he is all about, but are also intimidated/feel sorry for him....just like I was. However, they are with me mostly, and I am such a different type of person than he is, that it is ALMOST benificial for them to see how a (reasonably) healthy person does life. They will be able to see options now....and it infuriates him to see that they mostly choose to be loving and optimistic, despite his iron fist of negativity and lies.
I was also under duress when I agreed never to leave this county during the original divorce negotiations. He still had such a grip on me psychologically, that I am shocked more judges don't recognize those agreements as temporary anyway. Now, after 2 years and more than an entire years' salary gone to litigation....I don't have a ton of faith in family court. If you go to court, you will spend a lot of money. That's a given. But if I had the kind of paperwork you have on him, and the knowledge of how getting the heck away from him would have improved my life, I would do it in a heartbeat. But the father's rights folks are well heeled, financially, and very dirty players...(a bunch of N's sticking together, I guess), so there is support for fathers NO MATTER WHAT. My ex sees the children as tools/pawns/collateral, all of which makes it tough for us who are so in love with our children we would throw ourselves in front of a train to save them (something these N's really use to thier advatage!!).
So, what to do? Start moving out of the energy between you two. He thrives on it. You will thrive when you get out of it.
Sela and others offered great, concrete advice. Start working on yourself. Start loving yourself first. Let what he does and what he says flow out of your emotions like so much dog feces you don't want to hold!! Just let it all go. Find ways to meditate, read books that bring you peace and to a higher consiousness. Find a therapist who can help you deal with such ongoing attacks (yup, they will keep on going.....and despite appearances toward the contrary, I do not always have a duck's back with this stuff).
Mostly, keep your chin up. Not being still married to this jack*** is the best thing you EVER did for your children. And don't feel TOO sorry for yourself or your kids. This is all part of life, of learning. Some of the best lessons hurt the most. Remember, too, that kids really only need ONE good parent to be ok...and you are it!!!