May I offer you congratulations on graduating in a couple of months?
There are things you can do now to let the 'crush' go.
Stop discussing personal matters with him. Keep discussions limited to your work.
What you have is young teacher who doesn't know how to set boundary lines with his students. He is acting like he is still in high school. If he doesn't learn how to distance himself from the teens he is teaching, he may end up in some seriously hot water.
You sound like you have your head on straight. Accept that he is off-limits for several reasons and go about your life. It will be easier if you start thinking of him in the same way you do the most 'professional' teacher in the school. When you start thinking of him as a 'friend' bring up thoughts of teachers who you are convinced have no lives outside of the school. Mentally put him in his proper place. It will help.