I know what you mean about the addiction. Why else would so many LBSs stick around and hope. I also am pretty sure that it is more guilt than addiction on the WASs side. In my opinion their addiction has to be milder because while we were waiting and hoping, they were out doing their thing.
On the OW issue, I would imagine that it must be very difficult on the WAS to cut it off cold turkey. We may underestimate the feelings that they have developped for this other person. Regardless of what they say, I am not sure I believe the line that he / she meant nothing to me. Not after a prolonged period. A fling that lasts a week or so....maybe. When we get into years, the WAS must be adddicted to OP as well.
I know the feeling of looking at your stbX over a cup of coffee and wondering what the hell happened? Wondering if this is all salvageable.....