Hi Maxwell,
I'm not Dr. D, and don't even play her on TV. I've noticed similarities between some of what you describe and my daughter's mom.
My custody case has been open for nearly three years and is approaching trial next month.
My ex is on her fifth attorney. It's my perception that she'll reject/avoid any person who may challenge her perspective.
It's also my perception that my ex acts in very childish ways in attempts to effect short-term gain, but she doesn't seem to understand the consequences of historical actions nor possess the expectation that people would judge her on the past. She seems pretty stuck in the present, except for all the out-of-context past tidbits that justify her dislike for various people.
So... my guess would be that she knows that she's successfully charmed you in the past, and that especially given the upcoming hearing, you will only judge her on being a friendly, good girl and hence be on her side at the hearing.
Much like her moving into the more expensive apartment, she really may be incapable of addressing anything except the present (i.e., I want this apartment, but unlike most people, I don't think about how I'll sustain rent payments into the future).
The most wisdom I can offer is that after having known my daughter's mom for nearly 5 years (and living with her for 18 months of it), the ONLY thing that I've been able to reliably conclude and predict is that she is utterly unpredictable in her approach to situations, and I can never anticipate her emotions of the day.
In short, you and I are rational people but there is no rational train of thought going on in your ex's brain.
That's my layperson assessment of what's going on, but I get at least a certificate of honor in abnormal psych for dealing year after year with someone who meets the criteria for BPD and Histionic PD.
Good luck at your hearing! Stay focused on your son and your own welfare. :)
DD