Major Crush

I have a crush on someone and it's making me feel like I'm in junior high because I don't think he likes me back at all. And if even if he did like me back, I can't imagine what kind of relationship we could even have together. But, when I see him I feel paralyzed and I don't know what to say. I freeze up inside and if he were ever to touch me, I fear that I'd melt or shatter. I know I should be excited about feeling so young and vulnerable again, but seeing him instead makes me sad and pessimistic.