Well, I went ahead and took the plunge! I am now registered for the triathlon, the mentor program (because I need as many people to allay my open water swimming fears as possible), and the training program (starting 5/11)! It took me about half an hour to register because I kept talking myself out of it, and then back into it.
Now it’s done, and since active.com doesn’t offer refunds, it is final.
I’m terrified excited.