Get yourself some renter’s insurance, in case she does break something of yours that is expensive to replace, but that you can’t lock up or store off-site. Take pictures of things she breaks that are yours, because even mugs from Wal-Mart add up.
Take other people’s advice on locking things up, to the extent that you can. Put important papers in a safe deposit box, which is a good place for them anyway.
VERY IMPORTANT: Because of the possibility that a drug raid by the police could end up in getting your drugs as well as hers removed, make sure that every drug you have, both prescription and OTC, are in correctly labeled bottles. You can be fined, and have the confiscated drugs not returned if you have drugs, even antibiotics, in say, a Tylenol bottle, along with some OTC cold medicine, and a single codeine cough pill. I learned this the hard way.
If cooking is your favorite hobby, you won’t like my next suggestion, but get a cheap microwave, and a dorm-sized refrigerator for your room. You can cook just a couple of times a week, maybe when she isn’t there, and make prepared plated that you put in the refrigerator, and then heat up. Some food lends itself to thing and some doesn’t, so there are something you may no get to have much of, but from what I’ve been told they are expensive meats. I’m a vegetarian, and this works well with vegetarian food.
You can get a really cheap microwave for about $40, and maybe cheaper if you try Goodwill. The fridges are spendier, but sometimes you luck out and get one at a pawn shop. When my fridge broke in my house, and It was going to take me about five weeks to get the cash together for a new one, I lucked into a $25 fridge at a pawn shop.
IANAL, and I am not in position to lend you a really interesting sum of money, so all I can offer are stop-gap measures that the the roommate get away with her bad behavior.
I hope she is seeing a doctor, and they are in the process of switching meds, for her bipolar disorder, borderline personality disorder, or intermittent-explosive disorder, and she doesn’t kill her next roommate.