I don't see what the big deal is. It is only a word at the end of the day. Words don't hurt anyone, the meaning behind it is what counts. If you didn't mean it, then it may hurt but she should get over it.
Who hasn't said something they don't mean when they are angry? Pushed far enough, I just want to say the most hurtful thing I can think of. It's just venting.
If you call someone a fat ****ing ginger ****, it doesn't mean you have anything against fat people or ginger people or sex or vaginas. Its just letting off steam and not a big deal.