Sorry we have to be bearers of such bad tidings!
Not your fault, I know vendors will tell you sure, it will be fine indoors. That's because all they care about is selling their "product." Next time try to find an established bonsai nursery with a reputation to uphold, where they care about their trees and about getting repeat customers. If you are going get a new bonsai tree, do some research first, figure out what kind of tree you want for your conditions. You posted this in Indoor Bonsai. If what you are looking for is a bonsai tree you can keep indoors, think about tropicals like ficus. Decide what kind of tree you want, research what kind of care it needs, and only then buy one.