It's already been said, but it would be best if you moved on. When you have a crush it's easy to think that that person is the only one but that simply isn't true. There are so many worthwhile people out there, it's just a matter of finding them. It seems like at this point you're more in love with the "fantasy" of that girl than the girl herself. Yes, she was pretty and maybe you had a nice conversation, but what do you really know about her? Things may not have worked out at all even if you had gotten to know her.
At this point you're doing yourself more harm than good. I understand you have regrets, but only by accepting those regrets can we make ourselves better. Learn from it and don't let the next girl get away so easy.