Don't do anything. Don't tell her, don't show her. Consider these: 1. It is illegal for a student and teacher to have a relationship. 2. Even if it wasn't, the age and power dynamics here are really inappropriate. 3. She might already be in a relationship or even married. Because of these, she won't give you a chance, and your only accomplishment will be making her uncomfortable and bringing administrative issues for yourself. Move on from this, don't indulge in seeing her or even thinking about her outside of class. And keep all interactions professional.