I haven't seen anyone get back together after a separation UNLESS it's understood that the separation is an attempt to heal the marriage. If not, it becomes too easy to become comfortable and all you're doing is avoiding the issues. The separation becomes a way of running away from the problem.
"the only time she felt positive was during our talk about the separation because it felt like we were working together on moving forward."
Total BS talk. She could have also just as easily have felt you were working together at moving forward with the marriage also. She should have understood your insecurities about the OM and not have gotten upset. Likewise, if you were feeling insecure, you should have just told her your concerns and not just checked her log.
If both of you are separating just for the sake of doing it, it won't work.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.