I was in your shoes 18 or so years ago. I had no idea a wife existed, and thought he and I were so happy. To this day I have no idea how he managed to hide her for a year.
I emailed the wife with evidence. At first she thanked me. Asked me to send her everything (I think what she saw really shocked her - he really did seem very genuine, and I knew all his friends, I saw holiday photos with his mother in them, etc.) - because by the end of that week, when she'd had a chance to have a good look at what I sent, and process it all, I started receiving threats from various members of her family.
Yep. She'd decided he was innocent after all (I'm sure he had his chance to get to her and lie his tits off) and before you know it, I had people threatening to come to my house and do all manner of violent things. I was threatened with broken windows, bodily harm, you name it.
I reported it to the police, and because I had a good friend in IT at work, they were able to trace one of the nasty voice messages I received, and there were arrests.
Nothing happened, but they ended up divorcing because she took him back and he cheated again.
I WOULD NOT recommend this course of action. He knows where you live so there's every chance you could go through what I did. It went on for about two years in my case, because his in-laws became so aggressive. Detectives became involved at one point. So much drama.
You have children, DO NOT do this. You don't know who she knows or how she/they'll react.