Tell the truth or lie?

Two of my really good friends are going to get a divorce. I've been friends with the husband since I was 14 (I'm now 33 and he's 34). It's his wife who initiated it because she's basically done with him and their unresolved issues. It's a long story that I won't get into but let's just say I understand why it's gotten to this point. My dilemma is this... Only I and my other friend know what's going on but he feels like our other friend is mainly the reason why his wife wants a divorce and called her a "home wrecker"; while I understand where's he coming from because she does add fuel to the fire and has been known to make untruthful statements, etc (which is why I don't talk to her about my relationship with my hudband), it's really his behavior and attitude towards his wife that's making her want a divorce. He thinks his wife is cheating and given the circumstances I can see why he thinks so (though she's not, once again long story); I've had to tell him repeatedly to respect the fact that she wants her space which he hasn't done and to stop snooping through her messages, etc. His behavior is destructive and is not helping the situation that their in, he needs to accept that it's partly his fault too (and like I said, given some of the shit he's done I don't blame her). Now as a long time friend, would you tell him that he needs to be held accountable of his part in the spilt or let him continue to blame our friend?