So far, telling has been fine.
In the comments, someone said I don't even have to say she doesn't live with me. But I do. Trying to pretend she does is the same as when I lied about having a daughter. People ask where she goes to school. They would ask about vacations, hobbies, holiday plans. Saying that she doesn't live with me saves me from having to lie. In 9 months, only one person, a student, has expressed any confusion about that. Divorce and unwed motherhood are common enough that most people don't ask for more details.
It's been refreshing. She came to visit me in August (with her parents), and I was able to show excitement to a coworker. Instead of pretending to have no plans, I could say that my daughter was visiting.
Yes, it's slightly uncomfortable. I wonder about other questions. I find myself trying to change the subject quickly. Still, all that is probably part of lying all this time. Overall, I'm glad I'm being honest. And really, it hardly ever comes up so usually I don't have to say anything at all.
Thanks for all the support everyone.