Michael being Michael I am really surprised by his restraint in that he didn't have Kay killed, wife or no wife, after she told him she'd had an abortion and not a miscarriage. Heck, I mean he had his own brother killed! I don't doubt that Sonny would have killed his wife if she'd done that to him! I mean, what else besides having an affair could she have done to have really gotten to him, except maybe turned "Rat".