I think i'd say that Irons is crazier, he found the whole death of the mayor's daughter nice, or else he wouldn't have left her body on his desk... and then took it away with him. >_> However gross that is.
Plus the painting you get one of the red jewels out of proves it, a naked woman being bound. (or something of the like)
Annette isn't crazy, she's a smart lady I think, but she's just distraught over what's happening and not really having time to react, I mean, she had to get her daughter to go to the police station on her own in the middle of a zombie invasion, which would play on your mind just a tad.
In addition William is now a monster so she's not gonna be thrilled about that and the fact he's after Sherry.
So, in my opinion, Irons is plain crazy throughout, but the strain of the outbreak (as mentioned above) plays with Annette's mind so she doesn't know what the hell is going on, she's confused, and as most humans do when confused, they react violently. >_>