Hi hhh, I'm not sure that talking to friends of his would be the best idea.
It's hard to predict how they would react, what they would say to H, and how H would react. And as objective as you may try to be, these friends will probably make some sort of value judgements.
In my sitch then (if you remember), I was very tempted to approach some of W's friends for help, but I'm glad I did not. She eventually did tell them herself ( a watered down version), and the impression I got was that they were sympathetic but were also firm on her. She was already on the way back by then, and it reinforced some positive things. But if _I_ had approached them ... I just don't know.
I did tell one of that group (friends of 20 year from high school - and I chose the one she was least close to) a partial picture, but that was when I was desperately trying to arrange a getaway surprise for her with her friends. It was a very uncomfortable situation.
Me 42 W 39 Married: 11 Jan 1998, T: Since 1992 First Bomb: Sep 2007 Confirmed A/OM: 4 Nov 2007 Kids: D10, S5 Reconciled and together again after (alot of) time and heartbreak. 3rd kid, S, born 2 Jan 2010.