oh honey, i dont kow if you were joking, but nononono dont key her car.
Although i bet its mighty tempting(and i, er, may have thought of it myself once or twice lol) but she will stick that on you as soon as it happens and id hate for you to get evicted or in trouble with the police.

My suggestion, if you are brave, is DO bake her something, or buy some flowers. If you bake her something, take it over, knock on her door, and when she answers say "Hi. Listen, i think we may have gotten off on the wrong foot. I'd like to fix that. I baked these for you as a show of my friendship".

It would be HARD to be BRAVE enough to do that, but if you did that, i bet you would have a good relationship with her from then on.

If your not that brave, buy some flowers and leave the same on a note on them at her door.