I forgave my ex. for breaking my heart but it took me a while to grow up and understand the situation; she didn't cheat on me or anything, at least not that I know of, and it was simply that she was young and still living under her mother's thumb and, well, she may have fallen out of love with me.
I don't talk to her, and I haven't spoken to her since the day she broke up with me. I was stubborn, and I couldn't just be friends with her or anything like that, so when she broke up with me (online... which was kind of fucked up, but, again, we were young at the time) I drove to her house, gave her back all her things, and that was it.
I guess my family has run into her a few times and said hello or whatever, but... yeah, not me. If I see her again, I won't say anything to her, but not to be a jerk... just because I wouldn't know what to say.