I found that, somewhere after Replay, my H reserved began to confide in some people he normally would avoid--a bullying boss who loves to gossip, a young female co-worker who had never had a deeply committed relationship, etc--so it's good that your H chose someone more trustworthy and close to him. At the same time, he sometimes wanted openly to share his mental turmoil with me (other times he was withdrawn and cycling). He also discussed his conflict and need to make a choice more openly with OW, I believe, rather than, as had been the case earlier in their "relationship," of pretending they were "just friends" helping each other.
I hope your H can find appropriate support who can help him find his way.
By the way, good work on the way you handled the mis-sent text. But do NOT give him "NJF." Saying "we're just friends" shows he's still in denial and finding ways to hang on to her. He's not ready to understand the book, so it would just look like guilt/control from you if you were to give it to him.
