So here's what I wished I would've said:
"First off, fuck you. You have no goddamn idea what you are talking about because you watch too much Fox 'news' and have your head shoved so far up your ass you're just a sphere with arms. Secondly, this is America and we are all illegal. Unless you have Native-American blood running through your veins, you are an immigrant. Finally, the America I love is a land of opportunity. The America I love embraces diversity and reaches out to help people. My America is welcoming. My America wants kids, ALL KIDS, to succeed and learn and contribute to the greater good. And my students, even and sometimes especially the ones without paperwork, are the best damn people around except they have to be exposed to your racist bullshit that constantly places them in a corner or makes them feel like they're not worthy. My job is to teach kids and it is more than a job but a calling and a passion. White, black, brown, gay, straight, trans, American, Mexican, Asian, rich, poor, homeless, abused, loved, whatever. They are all my kids and shame on you for even thinking that some of my kids are less important or deserving than others. Now gtfo."
But I didn't say that at the time and for that I'm sorry. To my students, especially my beloved "illegals" I apologize and I promise that next time I will have your back.