Isn't There an Adult Around?

This happens about once a week to me. I am going about my day with my girls and something crappy and unexpected happens. This time, it was a spider.
I have made a lot of effort to keep my arachnaphobia to myself without transferring the fear to my kids. However, spiders are really just that creepy and gross. I think most people find them creepy and gross, and that is perfectly reasonable because spiders are in fact, creepy and gross. And scary. I guess technically then, this is not a phobia because it is a fear based on a real and observable threat. The threat being logically that the gross and creepy spider IS going to get me.
This spider was the usual beige sort, toting a typical number of weapons (8 spindly crunchy legs). My girls went into the usual fit, where some of the screeches can only be heard by dogs (who are not helpful with spiders either). I grabbed the nearest shoe, then spotted my husbands sandels across the hall and grabbed one instead. I felt a bit of guilt but quickly set it aside convincing myself easily that the real reason I wanted his shoe was because it was bigger and more likely to hit and squish the intruder.
Nasty thing died easily on the first smack. But what I want to know is, how did this become my responsibility? Where were the adults who could be counted on to take care of this for us? Who's bright idea was it to leave ME in charge???? Ok granted I am coasting toward a 4th decade in life but how did I get here?