How did you guys cope with this type of thing when it happened to you
Not well. Not well at all. My sexual abilities failed for months. I felt like nothing but "plan B", like she only came back because the OM dumped her.
I read your "backstory", too, and replied on that thread. A later poster on the other thread pointed out that you will enter this marriage with "baggage"....
From my point of view, this is damn heavy baggage.
Too heavy, in my opinion. If it were me, I'd be finding someone else.
I tried to work with a counselor on my insecurities. However, bottom line, I was always going to be thought of as "second rate" and that was just too painful to allow me to continue intimacy with her.