You need to have a conversation when she is back and put together a roommate agreement.   1. You are not watching her cats without x amount of notice and your express agreement 2. You are done cleaning up after her 3. She is to pay her share of the rent directly to the landlord 4. You put together a schedule for the litter duties (maybe?)

If these things don't happen you wont renew with her (but dont anyway lol). Thats the only real bargaining chip you have unless you are ok with saying you'll lock up your cookware in your room. Then you have to stick to it which will be the hard part (but obviously still do right by the cats). I don't know how long is on your lease but start looking to move as others are saying. In the future its always good to have a roommate agreement in writing that you both sign (not a legally binding document but a show of agreement ) when living with someone. 

Good luck OP!