By her name most likely, if available, must be the prefered form of address, as people started to confuse ''Regina'' for a name. This can be used to avoid any form of judgement unless so intended, in which case it is entirely subjective, probably dictated by some in a sense that would remain open to interpretation.
PS: Hure is a very likely option, as it literally translated "lover", I suppose (akin to French cher "dear"), but the etymology of such a word has to be taken with a grain of salt and I advise (heavily, no less) against actually using it. Point in case though, it is said that pros prefer "Hure" over "Nutte" (e.g. in a certain Vereinsname). Accquired Latinism are of course a noble choice, and French a cheeper alternative that's a little more familiar today, e.g. 'Madame' vs. 'Mademoisel', 'Mrs' vs 'Ms', 'Frau' vs. 'Freundin' (where the first should represent like dame "domina" Freya "Venus", and the other as love, cp. Freier, freien, girlfriend, 'belong to the clan'). See also hoary, hehr, Herr (implying grey hair, it is said) and relatedly shadow (in the dark, unknown).