Purg - you have an enormous decision ahead of you. I think it has to start with whether you want to be married to this guy or not. Can you accept someone back into your life that cheated on you?
I hate to say it but we often rationalize our way out of what our gut tells is absoultely true. How often does one suspect their S to be cheating, all evidence points towards it, other people see it, and then it all happens to be some magical coincidenece of events that our WAS innocently stumbled into?
I don't want to be a downer here. I do hate to think that a great woman like you is getting duped. I do agree with everyone else here though, that you need to sit with this info alone, weigh it all, and whatever decision you make, make it calmly. If you confront, I gauranty he will turn it on you.
I'll give you a lovely firsthand example. My W left a trail of evidence that anyone with a brain would add up to an affair (and the guy is my cousin in another state). Someone hacked her email account and forwarded some FB messages he sent to her, to me and my S24 at work. My S24 alomost puked when he saw them, and he confronted his Mom. Before I got home that night I calmly polled some trusted friends both male and female and simply asked if these messages alone would mkae them feel like their S was in an affair. 100% opinion in favor of it being an affair, at least EA, and 100% said they would leave their S for just these messages alone, never mind the other factors.
When I finally confronted her I was pretty calm. We spoke for hours, she never denied it or confirmed it, which to me means it happened. Someone very close to me said watch out, she needs some time with this and will most definitely turn it around against you. Sure enough, the next morning the attack defense was in full swing. She denies an A to this day subsequent to this particular incident.
I giuess this is a long winded way of asking you to be very careful about how you respond to this (if you do)and take the time to be very sure about what you can live with.