I was recently accepted into a graduate school in my field, but I haven't heard from any of the other PhD programs I applied to (and am assuming that they're all rejections/waitlists if I haven't been contacted by now. In e-mails with a potential advisor at the school I was accepted to, he asked which other schools I was admitted to since graduate schools of a certain tier generally accept the same group of students. How do I tell her that I haven't been accepted to any other groups (only MS programs) and do I tell her this at all? I don't want her to feel like she was the only person to make a mistake by accepting me.
You haven't been not accepted, you haven't heard. There's a difference.
"I'm still waiting to hear back from a couple other places." Should be a sufficient answer. If you want, a light quip about her university apparently being really on the ball.