When we were young but now depends upon who's wearing the pants, as they say, and not taking marital status into direct account. The term 'mistress' is most often used in a negative context on this side of the puddle, overriding its primary usage, and originally masculine terms are assumed for both genders where there's no common neutral term; another area where political correctness strains the language.Would that not be webmistress?
8-)