What really irritates me on that is that a 15 year old girl can go to Planned Parenthood and get those pills without her parents even knowing.
But in all seriousness telling your wife is a gamble. On one side, if you can't be up front and honest with your wife who can you be? On the flip side, if you get in a serious argument all she has to do is phone the police and you're in deep shit. But then again when she sees how fast you put on a serious amount of weight she's going to know you're on something and that might spawn a fight.