Wow, TG - that is some good advice. CS does have a choice here. He doesn't have to be the victim to her behavior, actions, etc.
To me, and again I haven't read his whole sitch, when I first read this, I got this "inner, knowing" sense that ... it was freedom. Yes, there is going to be a lot of pain, but maybe a finality? A real door closed for another one to open?
I read this quote today - sorry if it's not totally appropriate - but maybe down the road - "What the caterpillar calls the end of the world, the master calls the butterfly."