Well, you are free to explode here if you want (so to speak).
I can imagine your frustration. Especially with that girl. I'm not going to go off about her. I don't know her, so I can't say things like "that bitch, who needs her, you're too good for her" (though you probably are). Though I will say even if she wasn't interested, she should have just turned you down. Laughing in your face was unacceptable, and I can almost say for that reason alone you shouldn't pay her any more mind.
I don't know if this'll make you feel any better, but I can share something with you. When I was in high school, there was someone I kinda liked, and they were nice to me. But I never got the nerve to ask them out because I was intimidated by the vast difference in our popularity, and I've regretted it every day. Even if they laughed in my face, at least I would have know, and not been left with an empty "what if" feeling. So at least you had the courage to try, and when you find someone else, someone better, you'll already know what it means to be rejected, so you won't have to be afraid. You'll confidently ask them out. If they say yes, great. If they say no, then they weren't the right person, or you just need to try harder (but not with this one, no one should laugh at you like that, that ignorant bi... ahem).