These are the words Taylor Swift wrote in the prologue of her third, in 2012 released album “Speak Now”. This line is brilliant advise and even though she fills he prologues/epilogues with wise words , she seems to have problems to take the advise, she gives to her fans, herself.
No one can deny that Swift's kind of telling her ex-boyfriends (and other people) how they made her feel is sometimes a little rude, but that is not the point. She takes the critic with a lot of humor (e.g. Monologue Song) what makes it impossible to be mad at her.
She is a little paradox: On one hand she believes “The [(ones) words] you use to intentionally hurt someone [are those to regret the most], but on the other she writes almost impudent songs about how people made her feel, and hurt her.
By having a closer look at the topic Taylor Swift you can even find a bigger twist: The big amount of her ex-boyfriends is astonishing; To concertize, one of them was Cory Monteith who died June 13th 2013. Swift's album “Red”, on which the song dedicated to Monteith, We Are Never Ever Getting Back Together”, can be found was released more than half a year ago, in October 2012.
“We Are Never Ever Getting Back Together” is one of her most popular songs, and not exactly friendly. Many people empathize because it is sung along so carelessly. You can't fail by interpreting it: She is trying very hard to get over the person she wrote this song about, and has got no positive feelings left for him.
Swift's official statement about Monteith's dead, a post on Twitter read "Speechless. And for the worst reason."

She could not know what would happen to her ex-boyfriend, but maybe she learned that you have to be careful with what you're saying, because it just might come true.