You know, I don't think I'd bother with blocking him. That's kind of punishing him two-fold: he gets blocked from communicating with you on FB, and his wife still gets to rip on him for him having had you as a friend on there in the first place. Thusly, I propose a 50% win, 50% lose approach: keep him as a FB friend, but limit your posting to his wall and such. It's 50% win because he gets to still have you as a FB friend and can still communicate with you through private messages if his wife gets all bunched up over wall-posts. However, it's 50% because his wife might see that you guys are still friends and get herself all bunched up over that and continue to get on his case about it.
I say stay, because he obviously needs a really good friend to talk to (maybe about a super-jealous wife), and it's not fair to punish him for her crazy. While we do not have definitive proof that she was making a crack at you in the post, it's not a far stretch of the imagination, as you've already demonstrated, so stick with him for a while on FB. Who knows, it may just get him to finally tell her to put a sock in it.