SPOILER ALERT* - I think he played his cards wrong.  He doesn't want to go to jail or kill his wife.  Leaving her to die in the snow while surviving himself would bring up questions.  Since she's worried about this scenerio, he should suggest they stay there one more night (if only for another day of freedom)to try and gain her trust and hope she loves him enough after getting over the initial shock to let him get away with it.  If he is truly evil and want to kill her it would be safer for him to repeat history than draw attention leaving her in the streets while driving home.  Regardless, knowing what he was capable of and her vulnerability, she should have subdued her reaction to not give him a "jail or murder me" ultimatum.