It's important for you to read these AND for your friend to read them... once you are both educated on infidelity (you are well on your way already) you can offer HELP to your H.

Right now he sounds like he's drowning and NEEDS advice. But he won't accept it from you. After reading everything above you will likley understand why...

If your friend find some way of motivating him to STOP thrashing about and understand his situation is making him ILL, he can work with your friend to get OUT of the affair and you two can try to work together again instead of as opponents.

Will your friend read this material?

There are videos out there, but not nearly as informative...