This is a toughie. His recovery work should really be a private issue when it comes to his thoughts and journaling. But whats done is done. The issue now becomes what to do with the info. If you bring it up then are you prepared for whatever outcome? If you never mention it, will it eat you alive, do damage to your trust? Not sure how risky his behaviors were but I can only tell you how I'd handle this....
I'd have a deep discussion with myself, therapist, friend, whomever to process what I found out. Then I would make up my mind if this is something I can excuse because he was in active drinking mode and is working to change his ways. Or is it bothering me so much that I can no longer trust him or worry about catching STD's (which as much as I support his privacy, risky behavior of drinkers ain't cool if it puts their partners at risk so it may be a conversation worth having).
Hard to say. Just think about this for a long while before and if you decide to act on it.