My ex and I have been broken up for two years now. She is dating my best friend and I dated hers. We both admitted we are only dating them to hurt the other. Not only that but we've been having sex ever since we started dating each others friend, which was about a year ago. We seem to hate the other one too much to re date, but we're still sexually attracted to each other. Every time we try to stop, it doesn't last long.