I guess I've always heard that friendship is the cornerstone of a marriage. It sounds like you and your ex have it in spades. When I read your postings, I would think you are a M couple doing things together.
I understand how difficult it must be to have the brass ring in front of you but just out of reach. If I ever get to a point like this with my W, I hope that I can maintain the discipline needed to keeping developing the friendship, but not place an overpowering amount of pressure.
I don't know. My W and I became involved as a result of developing a friendship first. She was the only one I ever accomplished this with. One thing that gives me hope is that I remember her saying to me that she missed talking to me (i.e friendship). Also, the bringing up of memories and things that she likes about me.
I don't see how it can hurt to stay involved in her life. Maybe, an occasional "inability" to spend time with her will keep her from taking you for granted, but why not give the friendship a chance to blossom again and that love will further blossom into the love that made her want to marry you.
Sorry, Bruce. Just my $.02. Really comes back to patience.