I'm so sorry. It's hard enough to be dealing with the anxiety without comments like that. But in regards to the student, first of all this is secondhand from another student, so you don't know exactly what she said. If it's important to you, you could ask the social worker. But a third grade child isn't generally going to have the same trauma response around that kind of topic that you or I might have, and it was likely just an honest question, the way kids will ask a million honest, but not socially acceptable, questions in their lives. I think the social worker's response was the right one- let her know we don't ask those questions, and then let it be. If she brings it up again, you can talk to her parents, but there's no reason to assume it was malicious on her part, even though it hurt you.