^^^ This is you circular arguing with YOURSELF. Stop all this thinking about her and get on with your life without her or her bullshit in it.
I repeat:
Get back out there and start living your life as if she was never in it. You've stopped having tawdry extra-marital sex with her a year and a half ago. It's time you put an end to your misery.
Even this thread has you OCD thinking about her. STOP the merry-go-round you are on. If you had done that sooner, you'd be indifferent to her by now but you cling to the drama. Ask yourself "why?"
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion