Why does it hurt soo much??

Why is it that those we love the most have the power to hurt us worse than anyone else? You know it is like the words they say cut worse than anyone else no matter what the words are? The man who is the most important to me in the world said something to me earlier and I just can't shake it. I have really been trying, honest! But no matter what I do no matter how much I try to distract myself I can not let it go. I have not said a whole sentence to him since like 11am and it is now 8:30pm. He has not actually been trying to talk to me either though so no difference I guess. But sure makes me madder. I have tried to relax and read to cool off, nothing. I have tried to clean and throw my concentration somewhere else, nothing. Oh well...