lol, firstly what happened? im sure you can resolve the issue without any violent or threats to each other.
Exactly why is she targetting ur "skyline"?
There isnt much you could really if she did keyed your car as that couldve been anyone! photo proof or a camera proof could do the job! its pretty hard to pin point her even if she said she was going to if you got no proof of doing it, as she would also deny it if u bring the situation further.
i suggest you talk it out?, or park ur car in the garage at all times for the next yr or until shes over it haha.