Yet, my H's affair and our separation has now lasted 20 months. He has not ONCE hesitated or expressed doubts about his decision. OW is his soulmate, blah, blah, blah and he just does not see us ever reconnecting romantically. He says OW makes him happy and they are good for each other. Their affair is only getting stronger now that they are public and very serious in their R.
And yet you still want to pursue him (short of ML with him) . . . why?
I think you need to ask yourself, Why do you want to be with someone who -- for over a year and a half -- has demonstrated by way of an unrepentant long-term affair that he doesn't want to be with YOU?
Each of us has to make our own decision about how long to "stand," and reasonable people can (and do) disagree about how long that can be and still be healthy. But even the most die-hard long-term "stander"/MLC types usually distance themselves -- often separating themselves completely -- from teh affairing/MLCing spouse, and they don't continue to pursue after 3-6 months or so.
I'm not familiar with your sitch, KG -- have you done any reading and self-work on co-dependency through your ordeal?