"When people can walk away from you, let them walk. Don’t try to talk another person into staying with you, loving you, calling you, caring for you, coming to see you, or staying attached to you. When people can walk away, let them walk. Your destiny is never tied to anybody that left."

It's obviously a piece of cake doing the last line of the quote. But we know, especially who are left by our xxx, that it's not that easy !!
Anyway I got it from internet a while ago. But I can't remember who the writer is.
I ever heard this line, in the film and also in the radio (an announcer said it), "Never talk to someone who broke your heart. Whereas with your ex who dumped you first. It's a big NO to befriend him again. 'I'm happy as long as he's happy'. That's a bullsh*t. How can you happy if he's with somebody else instead of you? You, the one who love him head over heels. You, the one who would stay up all night just to be the first who wish him a happy birthday. Coz there's no way he can come back to you. You still have your OWN future. And it's way to be useless if you spend it to mope about him, who doesn't love you back. Keep it in your mind."
You know what, I'd love to be the announcer instead of the 'you'.

"It hurts to look at you anymore, it hurts to talk to you anymore, it hurts but yet I do it. I find myself looking for you, and see you. The only thing is, is that you don’t really care. It hurts a lot to see that you don’t care, maybe one day, not any day soon it will stop hurting. You know what they say you always remember your first true love."