Hi lucy.
I don't usually post on this side because I don't really have overly difficult F&F stuff in my life, but wanted to respond to this. I never had a serious intimate relationship with a person who had these narcissistic traits in "pathological" measures (and am very unlikely to ever be in that situation I think), but I have worked with many at different points of the spectrum. I usually manage these situations very well and also get along with the people we are talking about pretty good, most likely because I am either very averse or unresponsive to manipulation. I just felt compelled to respond to this, because once again, I have to work directly with someone who seems pretty seriously on the difficult end of the spectrum, in my new job... I repeatedly find myself in work situations where I somehow attract these people at first, and then typically discover lots of people suffering from their behaviors in the environment, and then I make steps to set it straight. Sometimes it works well, not always.
I second what dandylion said about letting the lawyer do the talking -- someone who can communicate in a more unbiased way, see through the whole situation, and not be affected by it emotionally. I agree with the views that it's not good to try to negotiate or appear uncertain / visibly vulnerable / too accepting because those are exactly the points he will grasp on and use in the situation. Keeping it factual, business-like, and as direct as possible is best... and for this, it may be much easier to let the professional deal with as much as realistic.
I hope you will be through all this soon and the uncertainty and anxiety dissolves! I've seen such things around me so many times I know how difficult and complicated it can be. All the best
