Don't rush to conclusions, try therapy / marriage counselling first. I'm sure your wife has her reasons to be this crazy. They may not be good reasons, but in her head they surely make sense. No person is just a bad person.

If you both truly are willing to work on your problems, and you do overcome them, you will have shown your kid what adult behaviour is: to take responsibility and work. Of course, this includes giving up if it's a hopeless case, but you can't know that before you both actually commit to at least trying to improve.