You friend-zoned the guy who cared about you and had him help you get closer to your crush. The guy probably feels used. If he leaves the city as planned, it looks like you may not have this choice between the two because your friend will be gone. Don't play with your friend's emotions any more by trying to start a romantic relationship with him unless you've got the crush totally out of the picture. It's not fair to your friend. (Of course, it's possible that your friend is no longer interested in a relationship with you.)
Get your crush out of your system. You acknowledge that your crush previously couldn't give you the love and time you required. Unless something big has changed, what makes you think he can do so now? There's something about your crush that you find irresistible. Perhaps it's a love connection. However, I suspect you'll discover part of the appeal was the chase.