What she might be telling you is that in her opinion, it is not cool to relieve the feelings of guilt by burdening the other party, which seems to be her current stance. She might be telling you that she would prefer not to know if you had an affair. Since she shifts the conversation topic so much, she appears anxious. She might be telling about something that happened in her life in the past, or she might be telling about how she would prefer you to handle issues in the future in your life. It is hard to say but continuous discussions would eventually tease out where she stands. She and you might be in a disagreement on this one. Both of you have valid points to make. She might be trying to collect intelligence on how you would be expected to react in different scenarios, or, she might be awkwardly revealing her own vulnerabilities. From what you have described, so many explanations are possible that it is hard to say what your wife really thinks and what she cares about now for the most part. Too much ambiguity.