Presumably there will be an objective third party guiding all this? (you included mediation in your tags).
Let him be the one doing the yelling.
If you’ve ever played poker or chess, now is the time to put on your game face.
Even if he pushes your buttons, don’t give him the satisfaction of allowing him to see that he’s upsetting you emotionally.
But don’t back down either. Just calmly stick to your guns. If you find yourself tempted to take the bait, don’t reply until you’ve counted slowly to ten (or 20 if necessary :)
There’s no law that says you have to make am immediate reply. You’re allowed a pause to think (even if the only thing you’re thinking about is how to keep calm)
It helps to write down ahead of time which issues to be discussed are the most important for you. Decide what type of compromise you could live with on the lesser ones.
Know what your bottom line is on each issue. Neither of you are going to come away with everything you want.
Don’t let pride and anger get in the way of common sense.
For each concession you’re willing to make, decide beforehand what to demand from him.
Since he’s the one apparently being eaten up by anger and revenge, you’re already a step ahead.
Angry people don’t usually do well at thinking logically. Use this to your advantage.
The mediator will also be approaching this logically so the more you can keep calm and present your case in a rational manner, the more likely he’ll find it easier to be acvomodating to your viewpoint.
The more over the top your ex is,the easier it will be for you to be the opposite. The more mad and resentful he gets, the less clearly he’ll be able to think rationally.