Girls (or boys): Advice, please!?

Not gunna lie, sounds like a rough situation. However you have it somewhat easy in the sense that you're moving. Unless you're up for a long distance relationship I would try and ignore these feelings. Try not to complicate things before you leave. If I were you I would talk things over with Mike to see where you guys stand and set the story straight (whatever it may be). In regards to Julie, if you live by "chicks before *****" you will make things work however if you really do like Mike and he likes you back, I would talk to her as well before anything happens between you and Mike. Best of luck!