Conflicted Desire in the Classroom

I'm a professor in my forties, and I've been with my partner for years. Recently, though, I started having intense feelings for one of my students, who's also in her twenties. It felt wrong but thrilling at the same time. We had an understanding that it wouldn't go beyond the occasional flirtatious text or lingering glance during lectures. But last week, we ended up alone together after class and gave into our desires. It was consensual, of course, but I know it's not right. What should I do? Is this just a phase, or is something deeper going on here?