In one way you need to take this personally though. You, as an individual, have been labelled as racist and if that label sticks it could ruin your future, costing you your reputation, friends, opportunities, and so on.

I would be very careful dealing with this person, as no matter what their motivation is for calling you racist she did so at the drop of a hat. That's like pulling a knife out because someone bumped into you on the street.

She only needs to reflect for a moment to realize that telling you that she is "international"and Haitian could lead to this misunderstanding. If she continues with this instead of acknowledging that she vastly over-reacted, then I would consider her someone dangerous for you to interact with.