Yeah that part is hard .. its like being nice to someone who just stabbed you in plain daylight.
I did this .. I called it my 'Sylvester', as much as I hate games, sometimes this whole thing is/was one for me. So even if I did not feel like being PMA and all happy boy ... I noticed with my sitch when she was like that it really irked me, 'how dare you be happy when you destroyed me, our M and our family' ... so I realized .. Hmmm .. Science project time and I started doing the same thing.
During talks, drop off and pick ups, even hot button issues like finances (she knows those would irk me) I pretended I was 'Sylvester' walking around with Tweety firmly hidden in my mouth along with a Chit-Eatin grin as if I was the only one in the room who got the joke (And I actually was lol). A month or two of this drove her nuts .... and to be honest I loved it .... 2x4's be damned if you can not have a touch of fun with all this whats the use??
I really wish I would have written down more of her crazy .. like you the "Fair" topic. yeah ... let her twisted logic be there is no making sense of things.
I recall my W believed that 50-50 custody also meant me paying 50% of her bills ... ya know .. the ones she needed when she got her condo near the beach, sorry there surfer gurl, you buy your own surf wax.