You do have some kind of problem, and it is this insulting employee. She is obviously carrying more baggage than the cargo-hold of a 747, and the only way she can make herself feel big is by casting her little insults at you.
Your refusal to accept her apology was absolutely correct. An apology is not some sort of wild card that an insulting person can play whenever he or she makes an out-of-line comment. An apology not only is an expression of regret, but it implies that the person will not engage in the same offensive behavior in the future. Your fellow employee is not offering you a real apology, and, as a result, it need not be accepted.
If you must have contact with this person, you need to assertively indicate that her insults must stop. Equally important, you should let her know that if she offers you a real apology, you will offer her a real acceptance. And, if she decides that she would rather continue to insult you, then you should decide to discuss the situation with your supervisor.
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