@peetrj,
It certainly is suspicious ...and frankly with my experience ...your wife might be thinking about cheating if she hasn't done it yet. I'm really sorry.
Have a phone number under the name "sex" and then telling you you did it??? That's well off ! Have you tried to a serious talk about it? You have to do it if you seriously want the whole truth. Again, I'm really sorry about this...there's nothing worse than being played like this. Especially from someone that you love so dearly.