Prepare for It. This one is easy. All you have to do is smile and say "Thank you so much for your support. I've enjoyed my time here and I've learned a lot from you. Let me know what I can do to make the transition easier." Are you always going to get reaction number five? Probably not. But if you look for the signs, you can likely anticipate your boss' response, go into the conversation prepared, and come out stronger on the other side. Then, you can breathe a sign of relief and start looking forward to starting your new position.
Or meet up with said colleagues at an industry event, because the world is awkwardly small. So it's in your best interest to make sure that your resignation letter is clear, concise, and polite. Here are some best practices you can follow to make your big exit a professional one.