My first break-up sucked hardcore. We'd been dating 9 months. He cheated on me, plain and simple, then got his other girlfriend preggers. He broke up with me and I didn't find out until afterwards. He got hit. Hard. But not by me. By some friends of mine. One of whom became my boyfriend several months later.
My second break-up was after only about a month. She broke up with me and it was a mutual thing, we both knew that we were better off as friends, and that's how we are. She's one of my best friends.
My most recent break-up was the hardest. Mostly because I was the one who called it off. Alex was a great kid and I thought I loved him, but after 8 months I started to notice a lot of things about him that really ticked me off. So, I (being the coward that I am) wrote him a note and tried my best to explain everything. One point being that he was obviously still in love with his ex (they're back together now). I gave it to a mutual friend and just said "make sure Alex gets this" and he did. The kid I gave it to? Possibly the best kid in the world. John has become my "one person" the one you trust above all others (except, perhaps for Erica...but she's basically my sister). He's always been there for me since we've really gotten to know each other.
We're not dating, but if we do and it doesn't work out, that break-up is going to be one of the hardest times in my life.