FH: the call was not painful, it slightly got me off center. It is still surprising and it was a bit of a reminder of the early days, when I was still engaged and was constantly being belittled and attacked.
I have had many firm boundaries, and W generally holds to them or I will enforce them (which can include ending calls). There were a couple of times in the past 2 years, one time she was attacking/insulting my current partner and I repeated a couple of times firmly that it was not ok, and when she couldn't control herself I ended the call. The other time was about finances and I calmly repeated twice that if she does not want to stick to our agreement we can finalize a divorce, and the second time she calmed down and we continued.
So it's hit and miss, and as boundaries should be they are not there to control her behavior, rather to set firm lines that I will not allow to be cross and will remove myself. I have a lot of experience dealing with highly disordered people (including NPD, borderline and sociopath behaviors) and elements of her behavior pretty much overlap.