Well the better thing that you can do is to start spread rumors about her with some friends, like for example things that are real, but just make them bigger. I would use against her the fact that she live into filth, then invent something on animal neglection, and other various things about her that may be true, don't say things that are improbable, just spread rumors that have a little part of thrut. Then start to say arround your friends that you heard her saying nasty thinks about them, just as she told them that you are highmantenance, say something that you know may hurt them, and then told her that those friend said something mean about her house after visiting... You have to make confusion between her and the other friends, expecially start with little things and just watch if they confront each others before continuing with really awful rumors. Then proced to put some photos of her cat on Craigslist or other website that may attire people that want to adopt a cat, when you find a people willing to adopt just kidnap the kitten and bring the cat to them, then let a window open and blame this for the lost kitten. Nothing bad will happen to the cat but she will actually believe he runned away. When you know that you are going to move, some day before you leave make sure to create some little damage to the furniture, you aren't on the official lease (or are you? Then don't do obvious damage but really little or hide damages that she will find in future) so she is responsable to pay the damage to the landlord.

The most important part is that you start to gaslight her too, expecially in the beginning, just change spot to things or start to have dialogue and then try to bring those dialogue later maybe 3/4 days later claiming she told you differents things or you told her something you know she is not okay with and that she agreed before. Then you can start to spread rumors when she is really confused. But it is better if you do this not too early before move out of her house, be ready to have a plan b.