Im freaking out

My bf just announced that hes moving out and into another state next year. Im freaking out because now we’re probably going to be a long distance relationship and its making me sad asf. How am I going to go without seeing him irl?? We’re going to have 3 hours between us and Im scared we’re going to start being distant with each other. Im the clingy one in this relationship so the fact that hes leaving makes me wanna cry my eyes out. But at the same time I want to be supportive of him because I love him so much. What should I say to him???