General

Forget whether it's cheating or not since this is just a word, and what might be considered cheating in one relationship might be ok in another. It depends on the type of relationship you have and the understanding between you. So the issue is more like would you're partner would be upset if they found out. In your case I guess they would or you wouldn't have asked if it was cheating in the first place.

I'd say no, it's not cheating if you tell your SO about it.

It'd be like going to a BDSM dungeon once a month...or a movie by yourself they wouldn't like.

If you hide it, yes. If not, then no. Life is too short to sacrifice what you really want and if you choose to be with someone who isn't into it, well, you settled and you have to live with it.

With open communication and understanding, this shouldn't even be an issue. Treat it like you treat going to a movie alone somewhere.

Keep it a secret and its bad. Bring it up in conversation and it'll be fine.

If you're even lucky enough to find someone close enough to you who'd be into it you'd have a good start.

hiding is cheating, communication is always better in this situation.

You can't be in this kind of a fetish without having an open mind in the first place.

Yeah it's cheating ;-)