That's a tough one, because you're already married. (Although, you just said, "A Wife", so I'm assuming it's yours haha)
In all reality, you needed to figure that out before you got married, and make it clear that you couldn't be in a relationship with someone who doesn't suck cock.
At this point, you could just cheat on her, and get head elsewhere. Or, you could tell her that you don't want to have to go elsewhere, but will if that's what she wants.
Honestly, though, guys are lucky when and ex or a father figure already got there and started to lay the groundwork. Head is fine, but you're going to want that throat. And if you're married, she needs to understand that. Exboyfriend sounds like he was on the right track.