Oh man.. When our crush gets even hotter.. Ya, that is though. I know the feeling bro :((
Look into meditation. Learn to meditate properly, there are good books on that. Learn to acknowledge that things are impermanente and unsatisfactory. Try different ways of viewing experience and see which one decreases suffering. When you are feeling badly because of him, look into your thoughts and notice how they dissappear. Does that help? If not, try to widen your experience. Use your sensory doors, hearing, sight, taste, contact. Listen to the sounds and notice what you notice. Same for sight, etc. (Sorry for the rambling, I am into meditation, if that's not obvious)
Other than that, just keep busy. Find a hobby. Be with your other friends. Make new friends. Join a gym, etc..