"Financee". I don't know if that was a misspel but I'll be darned if that isn't possibly one of the most apt terms in a lot of relationships.
"The Current Mrs Price". It keeps her on her toes.
I refer to my girlfriend as "nonexistent"
i hate SWMBO with a passion. just makes me cringe.
Toots.
If I was in your position I'd probably just say wife. You're acting like it and it explains itself if you're asked.
An uncle of mine still introduces his wife as his "first wife." They have been married for 50+ years.
Possible downside: If you happen to reside in a state that recognizes common law marriage, cohabiting for the prescribed period of time while holding yourselves out to be husband and wife just might render the point moot.