Military boyfriend

I’ve been having a rough time recently because my boyfriend just told me he’s going to join the Air Force. I love him and I’m trying to be supportive but it’s very hard and I am upset about it. We’ve been together 3 months and I don’t want to break up with him, but long distance just isn’t something I want or know if I can handle. Am I being selfish? Or does anyone have advice on how to deal with this?