I've gone back and read most of your threads and my sitch is very similar to yours. Bomb dropped, H didn't want d, told me I could have everything if I wanted d, I didn't want d either. But, in our case, he has never told me that it is over with OW. Indications are that it is. Things are different, but I'm still in limbo.
It is inspiring to read that it is possible to work on the sitch and still remain sane. At least, you appear to be as sane as anyone else on this board! I really appreciate everything you've posted on detaching. I'm working on that.
This post about imagining is great. Picturing myself and H as old folks, still together after all those years had a very calming effect on me for some reason. That is the mental picture I need to focus on when I have to thought stop. My imaginations need to be positive about H and me. And I'm no expert, but I think you are right about the difference in positive thinking and imagining.