First, I will explain the concept of the refuge vows. The refuge vows are there to help you maintain a mind of refuge. That is what I believe. However, there are many benefits to keeping your vows. These are:
we become a pure Buddhist, we establish the foundation for taking all other vows and many others.
To break a vow, the four factors must be present: intent, action, completion and rejoice. So, if you have completed all four then you really broke your vow. Also, on the ordinary daily level, even if you do not have intent, but you are bitchy and sarcastic, if it hurts the other person, whether you break the vow or not, you collect negative karma, because the other person was hurt. Also, if you speak softly and gently but your intent is to hurt or you are just careless resulting in another's cause of pain, that would be very bad also.
Also, sometimes when someone is bitchy to you, it might hurt but the intention is not to hurt but to help you become a better person. Then, you would have neither accumulated negative karma, nor have you broken your vows. But, of course, your speech must be skillful.