Yuck, I'm all too familiar with the stomach-dropping sensation of picking up the phone only to hear the "dead," almost hostile voice, when the last time you talked to him he was happy, loving and nearly himself. Be warned, this lasts well into the reconciliation period. The good news is, though, that although they go through peaks and valleys, peaks and valleys, after they've hit rock bottom, each valley is still a little higher than the last.
You stated that your ex was "atypical in needing time to trust the changes." I'm assuming that was a typo, since he's certainly quite typical. But, don't take it personally when he's "off" with you--it's really not you, it's him that he's struggling with. As LBSers, our primary focus is the relationship, and we assume the WAS spends a lot of time analyzing it as well. In fact, they're so depressed that every aspect of their lives seems overwhelming and frustrating, so that the relationship is only one small aspect of their revolving gloomy thoughts.
About the OW, what makes it hard to end things with them is that she is a fantasy. The MLCer doesn't really see the human being, he sees the solution to all his misery, wrapped up in one person. Her looks, her values, her compatability to him--these are often left out in the fantasy he creates about being in a relationship with the ideal woman. He fantasizes that she will fulfil all the empty places in him, and make him feel WONDERFUL. (Because that's what affairs are about: how the cheater feels about himself.)
After a while the MLCer sees the reality rather than the fantasy--he's still miserable, even though he's with her. Sometimes he breaks up with her, or goes back to his previous relationship. But, until he's really dealt with his issues and understands that true happiness comes from within, not from someone else, the fantasy that someone else out there could make him feel better is still in the back of his mind. It's like a drug addict, thinking, "One more dose of her will make me feel good again."
I guess what I'm trying to say is, your title of "Over with ow yet or not?" sounds as though you hope that once he's broken things off with Helen he'd be ready to court you again. More likely, though, he needs the time to process the loss of something that he'd hoped would fulfil all his needs. Sometimes he'll forget that she wasn't the fantasy he'd built her up to be, and be angry that he gave her up for you. And finally the guilt will start to hit him and he'll batter himself for what he put you through. But it's all a very long process.
So, keep focusing on all those parts of your life that don't involve him, because those are the parts you're going to need to throw yourself into if/when he does come back. It will be some time until he's able to give you the relationship that you've visualized over the past 2 years, because he's still stuck in selfish mode, not partner-mode.
