If the word Schatz is used (and it more than likely will be), then you can Du each other.
One other thing:
sigh
I have NEVER known (being German, I mean) where exactly a prostitute “fits” in German culture, but (jeebus, I HATE this term) for all intents and purposes, these ladies accept this as “just a job” and lead very normal lives right along with their profession.
Yes, they’re ostracized to a degree, and yes their kids must take some abuse in school, and yes the neighbors know, but somehow, in that very fine culture, there is a tendency toward tolerance.
I don’t know how to explain it any better. Perhaps our European Dopers can shed a bit more light on this?