So... What do I do now about this?

I've been very committed to mourning about my past, failed relationships. I've really wasted a lot of time being in "love" with someone, and now it's fading because I realize that I'm only torturing myself. Since August, I've been sort of friends with this guy who lives here for the year as a foreign exchange student, because he's staying with my best guy friend. Since last month, I've become better friends with him, and though I've been attracted to him, I've still been too distracted to notice. Now, I wouldn't say he and I are best friends, but it's a very heavy burden now that I've realized that I feel for him. Not only our friendship is in jeopardy, but I'm also stressed because he's likely to be going home in a few months. My major stress is that he could never think of me the same way. I can never tell if we flirt, (it's complicated) but he and I get lost in conversation and tell each other a lot. Lately, my confidence is low because I feel almost empty about this, I avoid talking to him because I feel that it's obvious, and that honestly, I'm no good. He's dated another girl and he had a huge crush on another, yet I don't know if those feelings are still there. it makes me feel that our friendship means nothing and it adds to the feelings of insecurity. Though I'm happy and confident in all other parts of life....