Glad to hear that you're not rushing into anything. Now is the time to sit back and listen while protecting your heart. Maybe her sudden aha moment came because of her medical condition. Something like that can certainly make someone understand what really is important in life.
The other thing I wondered in reading what you posted was whether you knew if she was still with OM. So many times (and this happened in my case), they do a sudden about face when they break up or have a falling out with the other person, but in reality that doesn't mean they're done. They just seem to run back to the place they feel safe.
After I found out about husbands first affair, he decided he wanted to work on the marriage. A little over a year later I found out that he was back at it again. I remember going back to my therapist, who I never thought I would need to see again, and she told me that she couldn't say definitely but he obviously still had issues that needed working out, & to prepare myself because this could easily happen a 3rd time.
I really don't know that either of these scenarios fit your ex, but until you know more, this could always be a possiblity.