If you received a nice message from an ex through Facebook would you feel obligated to respond back?

The relationship ended with me breaking up with him and him pining away for me for eight years. This was years ago. I messaged him last Thursday through Facebook & I'm sure by now he won't respond, but don't you think you would respond, even if just to say, "I wish you luck, I've moved on?" I think it is only courteous, especially given I was nice with my message & I wasn't mean to him when I broke up w/him. He knew he treated me poorly and that was why I ended things. Thanks.