I'm so sorry sweetie! I know these things are really hard, and especially when you can't get your mind off htem no matter what you do.
Vashti's right, stop second guessing yourself on all this, you can't blame yourself for anything that has happened because you don't know if things would have been different or not.
And as hard as it is you just have to look at the whole situation as "It just wasn't meant to be". I know there's tons of guys out there who would be want to be with you and adore you the way they should. Your a good person and you deserve someone who will treat you as such.
Hang in there hun, things do get easier, but it all takes time!
If you can't handle the thorns, don't crave the rose!!