If you "choose not to broach the subject or try to integrate this into my marriage" and you go ahead with this, there is a significant risk that not so long afterwards, you would no longer be "happily married".
I don't know what you mean by "fetish" in this context, but most anyone hearing about it in those terms would assume that the session turned sexual. And when your wife finds out, are you going to be able to prove otherwise?
A slap on the face and an order to get out of the house is the least of what I would expect as consequences.
The consensus here is pretty much that if you need to "experiment" with another person without the specific consent of your SO, then you should get out of the existing relationship first. As in divorce.
