Most Helpful Guy
Well of course you are going to make him sad/hurt him. How would that not happen?
but you can make it as straightforward as you can. You just tell him that the two of you are not for one another. Don't say stupid stuff or play games, just tell him. And make it fast and easy. it is going to hurt, but at least he knows and can move on.
Most Helpful Girl
You: You know, your ex is attractive.
Him: Wait, which one?
You: ME! //runs away laughing//