OK, if he won't go to therapy then you have a few choices
1. supply him with reading materials 2. Supply him with video materials 3. educate a marriage-frienly friend to offer him guidance
In the case of 3 above, try to get THAT person the reading and video they need and they can FEED that to your H through their voice... its almost as good as therapy...
All your H needs to know right now is that :
1. The only way for him to KNOW if he can repair his marriage is to EXPLORE that. 2. The only way he can explore reconcilliation is to END contact with his friend (affair partner))
That last point I will expand on.
If your H wont admit to an affair he CAN acknowledge that this person's INVOVLEMENT with yoru H is NOT constructive and is hurting YOU. Your friend can tell him that "regadless of what is or is not going on with this OW, your wife needs you to END CONTACT with her... shes clearly hurt and you need to keep away"
and as a follow up :
"If she IS only a friend, then you need to show respect for your wife and NOT put a different woman BEFORE your wife. If she's just a freind SHOW that by ending contact and setting your wife's mind at ease. No one is accusing you of anything, we just want to set your wife's mind at ease so you two can work togehter. Right now she isn't giong to work wtih you while you continue to be in contact with this woman."
Give your friend this sort of dialog to use with him. It's non-accusatory but gets to the same place - NC.
I have worded this in a way that he CANT refuse without incriminating himself.
If she's just a friend, then he should be able to end contact. If he can't end contact because she's mroe than a freind, he MUST end contact.
Your friend should start doing some reading on infidelity ... start with the article I posted here and the two in darksky's thread.