Frankly, the woman in your story sounds like a prude.
So, a rhetorical question meaning "Why can't a woman be more like a man?", then. "Prude." Classy.
The reason people add insult to injury isn't usually that they're just jerks. More often it's because they want to remain the hero of their own narrative, but they know they're being hurtful. Any story they can tell themselves for why the victim deserves it relieves the cognitive dissonance, so it's apt to be latched onto.
Does she think men think women don't actually urinate? Was she 14 years old?
Case in point. Any more insults you need to get out of your system to convince yourself your cause is just? She's fifty-something, by the way.
Are you familiar with how urination works, physiologically? In case you haven't given it any thought lately, we have muscles around our urethras that normally hold the urethra closed by means of continuously maintained muscle tension. Urination involves
relaxing them. Men typically don't have much trouble relaxing in the presence of women, so it stands to reason that women should have little trouble relaxing in the presence of men, eh?