I forgot to say, onit, he is a head-fucking tosser and you are dealing with him exactly right. He is bullying, delusional and his double standards are mind-blowing. You are disengaging and detaching beautifully, keep doing that. Of course he will be livid. Good.
I had this with my XH. He was an EA shit. He too treated me like an underperforming employee and barely met my gaze in the final few years of our marriage, the implication was that I wasn't even worth looking at, let alone an equal. But then, when I started actual divorce proceedings he went up to a new level of anger. He was so affronted: this then became the 'new crime' that I was guilty of, that of saying 'No more'. He's still not got over it. As far as he is concerned he is the victim of some kind of human rights abuse. We are 5 years - count'em - down the line from the split, and I am still the anti-christ. Presumably because, out of the blue, I filed divorce papers and stole his house and his children from him.
I assume this is what your STBXH is feeling - despite his outrageous behaviour of lying, cheating and betraying the whole family - he is totally affronted that you have the cheek to say 'No'. Keep saying No onit, you are doing great.