I am sorry that you were here and suffering from the devastating trauma as the result of your husband‘s affair.
I would strongly suggest that you not contact any additional coworkers. Should you reconcile with your husband, it would be awkward and very uncomfortable for both of you in the future if most of his coworkers were somehow involved.
That being said, I’m going to assume that most of his coworkers will not want to get involved and it could affect his employment as well.
Regarding your question about getting the truth, it is unfortunate that once the affair is uncovered, the cheating spouse chooses not to do the right thing by being honest and providing information.
I would suspect that this has gone beyond being purely an emotional affair. I would suspect that they did at least kiss (on more than one occasion) but I do not want to say with certainty that there was more physical contact between them.
However, whether they never kissed or had a full-blown physical affair, it’s still cheating.
It is up to you to decide whether the affair is a dealbreaker or not. To some people and emotional affair is just as bad as a physical affair and choose to divorce as a result. To others, an emotional affair is something they can reconcile from and they choose to stay together. Only you can decide whether you believe you can reconcile with your husband.
It might be wise to not make any major decisions about your marriage at this time. You are in a highly emotional state and may not be able to rationally make decisions that affect your marriage. Don’t be so willing to "forgive and forget" or choose reconciliation at this time.
I would suggest that you obtain your own counselor to help you navigate this traumatic situation. I think it would be very helpful for you to have someone who can guide you and counsel you at this time.
I can share with you that I was very set on divorcing my husband due to his midlife crisis affair. It was my own counselor who helped me to actually consider reconciliation. We are one of the lucky ones who have reconciled and are happy.
But I’m not the same person as I was prior to his affairs and we now have a very different marriage as a result.
I hope this helps you and please continue to post here so we can support you.