What happens when a couple takes a break then is ready to start again? Tell what happened during the hiatus?

i mean a long standing couple 5yrs+ we decided we had some issues we needed to split for a while and see if we came back to each other which we did. we werent apart too long but for 5 or 6 mths. i saw someone else who is a good friend of mine, he also saw someone else who he met. we both know this but wont address the issue upfront. has anyone been in this situation? is it best to lave it alone? get minimal details? or know everything about the situation? we both are done talking to them on that level and have agreed to work things out. I have minimal contact with my "fling" (he was a friend b4) and he has no contact as he just stopped contacting them when we decided to make things work. those with this situation would be best to answer but any opinion is good