Head vs. Heart

I'm desperatly trying to talk myself out of doing something I know I shouldn't do. I want to but if I do it will end badly, of that I'm sure. But sometimes it's hard to do what you know is right when your heart wants to do the other thing. It's like my heart wants to get hurt again. My head tells me the logical choice, what I believe is the right choice, yet still my heart tugs at me. Why can't they both agree? Why must everything be such an internal conflict? Life wasn't supposed to be like this. Something somewhere went horribly wrong. So which do I do, what I want or what is right?