Why do us blacks get offended when a white person calls us the "N" word, but we call each other the "N" word?

I think it's backwards. I am a black woman and I always hear people of my race saying ***** this and ***** that to each other, but the minute a white person says it....oh they done really fu cked up! Im not taking sides here but you really have to think about it....most black men can get away with calling females b!tches and hoes, but when someone white says it to a black team or person a black person is ready to beat sme azz! I think it is so ignorant! They say your not supposed to cross certain boundaries.....but aren't we crossing boundaries by calling each other these names in our own race? What do you think?