You went right back to the father/daughter dynamic.
from the very begining of this thread it has sounded very much like a "brother/sister" relationship, love life dead in the water; and her complaints, if she is re-writting marital history, or just plain fed up with you, are hers and are holding any intimacy back, hence you carry on like brother and sister. then the affair...
Do you know what the term amicable means? Do you believe it is possible to live with someone you love or once loved and think of them as a sister? God forbid you call her bluff, OIN.