Hi Movinon:
You don't sound like you're going totally crazy to me. I hear sanity in your voice.

I've not been through mediation but a couple of thingys in your post caught my attention:
1.
"Rules" i.e. temp. orders mean NOTHING to this man.
Prepare yourself for the idea that mediation won't mean much either. In other words, isn't he quite likely to act in a similar manner in regard to the whole process?
Possibly ignor agreements? Maybe just waste everybody's time?
2.
I will be going for ....
I think that's the only way he will hear anything or be made to pay
Be careful about using these kinds of phrases as they can be misconstrued as revenge seeking or worse.......gold digging. Rather, you are entitled to your half, your contribution, yours and your children's welfare/needs to be provided for, your property to be released or replaced, etc. Court might be the only way to settle this. You have been hurt by this person's abusive behaviour but all you want is what is rightfully yours, what you are entitled to, your share, etc. right?
3.
My fear is that he will deny all of this and absolutely REFUSE to negotiate or even consider that this might be factual info. (there are people who can corroborate my story, but getting them to commit to putting it down LEGALLY is another story). I don't think this will even be a bargaining chip for me in the rest of the deal.....
Do your best to ignor his reaction. Speak the facts and know the facts and be confident that you are telling the truth. He can deny all he likes. You don't need to hear him admit it or acknowledge it or react to it or anything else. Pretend he's a tiny wee bug with a voice so quiet you can't hear it or that he isn't even there.
Or if it's a matter of his responses being reported to you by the mediator, do your best to make simple statements: "That's not true". "The fact is........." "Regardless of his opinion, the facts are......" etc.
4.
as he will not even be able to wrap his brian around the possibility he did something underhanded
I bet you're right and he won't be able to admit the slightest fault of his own. Is this really about that? Is it likely that his denial will ever lift and allow the light to shine on his true behaviour? What matters now? Getting an admission from him or getting your fair financial share and letting go of him and his crooked/twisted/mucked up self?
I hope this helps a little. Hopefully others with more experience will be along shortly to offer you support.
It doesn't sound like much fun, Movinon, but it won't last forever. Soon, this will all be just a distasteful memory that you don't have to think about at all, if you don't want to.
Sela