Nataku, you make a lot of great points, too, and I'm really glad to have your advice. :) Thank you, everyone!
To begin with, I am NEVER buying another Betta from the location I bought Tian-Tian from. EVER. They never take care of their Bettas and they always look so dagum sick. :(
Secondly, I think I've convinced myself NOT to get another Betta right now. Even if I did, I'd rather just get another tank than set myself up for failure with two Bettas in a cramped, divided space.
:) So Tian-Tian will be my only spoiled brat for now. Huzzah.