Pippi, just hold your ground and stay as calm, cool and collected as you can. Be logical, have all the paperwork at your fingertips, stay rational.
What happened in my 4 way negotiation meeting with AH, and the 2 lawyers was that AH revealed himself for what he really was very quickly. His demanding, his ultimatums, his twisted "facts" did not go over well in the context of a legal meeting. He walked out of the meeting before it had barely begun and essentially threw a tantrum. Within 5 minutes, it was clear that he was totally out of control.
I persuaded him to come back to the negotiation, and I made sure that he knew I wanted him to have what he wanted most - his income stream from his retirement accounts and the rental home for income and as his "lifeboat". It was very difficult, but we perservered. He had a legitimate complaint about a financial transfer in which the bank apparently didn't put his money in the right account, so resolving that helped. Gradually the wind left his sales, and after 2 hours, he signed the agreement on the spot.
I believe you will find that people in the legal system - lawyers and Judges - are used to working with facts, the truth, what can be proven with valid documentation. Histrionics, power plays, tantrums are not viewed with favor, so people who do that discredit themselves quickly.
It may help if you think of this with you almost as a bystander; your AH now has a grand podium from which to reveal his madness, grandiousity, and his punitive, vindictive intent. And his audience are people who will see this for what it is, and they have the power to squelch him.
Think of him as Oz in the Wizard of Oz. Behind that grand screen with all its grandiose bells, whistles, noise, is just a very little man making a very big noise.
PM me if you'd like,
ShootingStar1