Feel Like I Cant Go On Anymore...?

I met this girl, 4 years ago, freshman year in high school, we instantly clicked, I developed feelings for her, well around senior year, i finally gathered my courage, and told her i really liked her, and she said the same, but that we should just try and go on a date first, this happened around december last year, so we talked immensely about what we would do over the course of winter break, then the thursday that we would go out, she tells me he aunt is sick, so i ask her what did she catch, but then she tells me she fell down the stairs, well for any other non-blind person, they would catch the signs here, but i didnt, i told her can we reschedule? and she says yes, sunday, the day before school started again, i see a picture of her and another guy kissing, the next day, a couple of my friends tell me about what they saw, my best friend, she goes, didnt you see the picture? why arent you mad?, i didnt even the know the answer myself, i just felt hurt, disappointed in her, i ask her, so you have a boyfriend? and she goes, yes, it just happened, and i told her im not mad, i just left it at that, so far we have just stayed friends, i just wonder why she didnt tell me about him, if i still mean anything to her, i kept telling myself to go and talk to her again about it, but i never did, we did have fun at prom, we got in the photo booth, we danced a little, he was there too, i do converse a little with him, i just cant really look him in the eye, well now, we are out of school, and it will be a little harder to find the time to talk to her, if i should, i cant do it over the phone or facebook, i need to be there, if im going to talk this over with her, so, i ask you, why did she not tell me about him? did she really stand me up? should i talk to her about what i feel? should i let her go? can we still be friends, despite what she did to me?