Crush problems...

So.... I started to like this boy probably about a week ago but a finally admitted it (to myself... and a couple friends) yesterday. He's a good person, no bad rep, not a player-type guy, he's really nice and smart. It's a small crush right now, but I know every week I see him, it's just going to grow and grow and grow until it's overwhelming (I know from many past experiences). Though, for the last two days, I've really been missing this guy I used to reeaaaalllllly like that moved away. I don't know if it's because I feel guilty for moving on, or.... I don't know. I feel like I can't move on because I didn't even get the chance to say goodbye to him. I just want some advice that will help me not fall too quickly and to help me understand why I feel this way. Thank you!