First off, I want to say that I'm sorry you've had to go through all of this, ray. Keep working at it, though, and you'll see yourself through.
It might not be the case with O, but I can say that things aren't always easy for the person who's decided that they can't be what their partner needs in a relationship and, as such, chooses not to be in a relationship with that person. Watching someone I dearly love, even from afar, try to find the quality relationship I can't provide has been one of the most painful and challenging experiences of my life.
Still, as MindfulAgony
's partner says, I'm committed to the person, what's best for her emotional health, not to a relationship with her (especially one which we can't have).
As for being friends with your exes, that's definitely possible. I remain friends with all of my significant exes and interact with them regularly, if mostly online (facebook has been a godsend for keeping in touch, since some live quite far away). I think this is possible because I genuinely love each of them, even if that love is no longer romantic. We might not have worked as couples, but that doesn't prevent us from working as friends; even close friends in some cases. Some of these women I'd dated and lived with for years and still manged to come to congenial terms, eventually, after our break-up. It wasn't always easy and it certainly didn't happen overnight (in most cases), but we found a way to make our friendships work because we still care about each other.