How can I support him?

Recently my boyfriend and I broke up a few weeks ago. Mainly his reasoning is that he couldn't handle the distance and that he's questioning his sexuality. He doesn't want to be so quick to label himself. It's just I don't know how to cope. I know it's hard for him. Ever since we met five years ago he's always had thoughts. What would you do? It's hard because I still love him. And was totally caught of guard when he wanted to break up. He's my best friend, I just can't imagine my other half not my other half. Ugh.