I would say it is not a bad thing to learn your wife's affair. My advice is to do nothing is better than do something, at least at this stage. I would suggest you do the following things:
1) do more research on the so-called affair- make sure it is TRUE
2) if it is really the case, try to forgive your wife- remember that the best punishment is your forgiveness This may sound ridiculous. Indeed, it is true for many of us.
3) change yourself- the affair indicates that there is something wrong in your life, including sexual life. You need to ask yourself- Do I love my wife?
4) change your belief about your life- accept the truth and consider to have fresh new life.

I would suggest NOT doing the following:
1) disclose the news to everyone related- if you do this, you will get trouble.
2) punish them
3) devoice

Lastly, I would say LIFE IS VULNERABLE.

YSI