Thank you all for the advice. Based on this, I think it is probably safest for me not to confront him or his family with what I've learned.

One thing I can't seem to shake - I worry that he will do this to another woman. What responsibility do I have to prevent some other poor person from going through this? He is a professional liar, highly intelligent, and very convincing. I know he wants children, and he is so obsessed with appearing to be the perfect "family man" to his family and friends that I am sure he will do this again to someone. I have the benefit of being able to cut him out of my life entirely, but the next woman won't have that benefit if they have children.

I have no desire to keep tabs on him or know anything that happens in his or his family's lives going forward. But, is it really okay to remove all contact, knowing he will probably do it again to someone and I won't know to stop it? 

My divorce from my husband was finalized a few months ago. For over a year, he told me he wasn't happy, and I did everything possible to please him. When I felt like we finally were making progress, he would always say that he wasn't happy, but could never offer any specific things for me to do to make him happy. The entire end of our marriage, he made me feel small, worthless, and completely powerless. 

Months after our divorce, I am now discovering that he was unfaithful with men, certainly during our marriage, and likely for the entire time we were together (10 years). It feels like I am starting the healing process all over again, and I am so angry. He does not know that I found this out, and I do not have pictures to prove it, just confirmation from other people I know who discovered it but were afraid to tell me until now. When they told me, so many inconsistencies with his behavior suddenly started to make sense. 

I told him during the divorce that I did not want contact with him because it was too painful for me. Do I confront him so he knows that I finally know the truth? I know he will almost certainly continue to lie, but I have so much anger, I wonder if confronting him might help me move on. Or, would telling his family the truth help me move on? They will also almost certainly deny it - they believe that our divorce was 'mutual', when in reality he left me without any real explanation beyond 'I'm not happy'. Are there other ways I can healthily deal with my anger? I feel like just accepting that he did this to me and moving on without taking some sort of action doesn't give me the self-respect that I deserve. At the same time, confronting him or his family will probably just be met with denial - but at least deep down he will know that I know the truth and see him for the fraud that he is. 

Has anyone else been in this situation? What advice do you have?