You get hurt only by people who occupy a big part of your heart. The more it hurts, the more important the person. Why it doesn't matter to those who hurt you I will never understand, especially when you know you occupied a big part of their heart too.
It isn't fair when you know a simple thought from them could rearrange you. All that remains is the hope that somewhere along the way you discarded a stronger more vivacious version of yourself. A fragment to be called upon when you have nothing left.
Beware of the term "best friend" or "soul mate" these are terms a lot of narcissists use to draw you back in, keep you hanging on and to further abuse you without responsibility. Don't you cheat on all your best friends?