I guess my worst break up would have been at the end of my reign in high school. I didn't really find it important to date in high school, I thought that it just got in the way. But then there was this guy who I had a crush on since I met him my freshman year. He finally broke up with his girlfriend of many years during my senior year (he was a few years older). So he called me and we hung out as much as we could from that point on (he was headed toward Wyoming for college). It was all so perfect and during those few weeks we planned our lives together. So come time for him to go to college, he asked me to wait for him and not give up on our relationship even though we were so far away from each other. Well.... I stayed true to my word. I guess an Ex of his (who dumped him after two weeks and called him a fag the entire time that I knew her) called him up. He promptly accepted her offer to get back together and didn't tell me until, I suspect, they had been dating for a while. It always makes you feel good when you get dumped for your arch nemesis. But that's not the end.... This guy and I were really great friends before the whole dating situation and this rehashed ex of his was jealous of that and refused to allow him to see or speak or even acknowledge my presence. About two years later he broke up with that girl (YES!!!) But not before my heart had been broken, Puréed, and fried in burning jealousy. Once night I went out to the bars with my friends and I saw a friend of mine that I hadn't seen in a while. So my friends and I head over to where she is and I sit down at the bar, and this guy who has his back to me turns around and it's him. He still makes me nervous to be around. We discussed how much of a dick he had been all those years and I told him that it was inexcusable behavior... and he bought all of my drinks that night. That didn't really ease my contempt for him.
Moral of the story.... Don't date your best friend, as right as it may seem... it only makes you hate each other when you break up.