I guess the stakerish part is one of perception and, yes, he (and OW) probably perceived it that way and if I thought you were in any way still interested in a reconciliation, then I'd probably suggest stepping away too.
She still reminds me of a Jeremy Kyle guest. I do agree you let the conversation play out for too long. I suspect the proper response is "I can see why you feel that way and I really don't give a [censored]" and then politely hang up. Both valid, both true, but these clever come backs only ever come back after the fact. I probably would have been dumbfounded at the sheer [censored] of the woman and have been tempted to say something very unclever like "oh eff off you miserable excuse for a human being".
I am with AS - don't worry about his motivations, or whether he is being manipulated or not. He is a grown man, capable of making his own decisions. Let him own them. The fact that he has avoided doing anything to do with the divorce might mean a lot of things. Could just mean be he is a lazy selfish self absorbed [censored]. Try not to waste any more energy on it.
Maintain, as you have through all of this, the moral and intellectual high ground. he will realise what he has lost eventually. Of course, it will be too late by then.
