Like the bed thing that has been brought up before, as starsky says above, these texts, convos, thoughts are not helping you any.

Imagine for a moment BTM, that YOU are now the OM. And she has no reason to leave her current R. And she could be enjoying these convos with you. In the same way that you might be entertained rehashing past Rs with old GFs. And how those twinges still sometimes exist.

And YOU may have intentions with these convos, but SHE does NOT.

ie. "Gee... I loved that old station wagon we used to have... such fond memories... 'member that time we took her to the grand canyon... those were the good ol' days... like they were just yesterday. Sometimes I wish we could just do it all over again, but unfortunately Betsy is dead and buried. Still, nice to talk about it."

Is there really anything to understand? Other than the facts that are blatantly out there?