My oppinion on this matter (as if it matters):
With freedom of speech, you can say whatever you want (with exception of when it does damage to an individual or business and it is a lie). Saying 'cunt' is legal, however, it doesn't mean that an individual with the same right to freedom of speech can not tell you how wrong it is and want you not to use it. Sure, you have that right, but we also have the right to show our displeasure with it.
I've learned that the word is probably the worst word you can call a women. If you want to use it, fine, but be prepared for a nasty response, and we can all watch as the fireworks go off!