ok, first, dont panic.
Take out the filter and keep running it in a bucket or tub of clean dechlorinated water. This will save your cycle.
Now change out all the water in your tank.
If you can, rinse it out with hot water. Refill with clean dechlorinated water. Place filter back in tank.
Bring temperature back up slowly.
Reacclimatize your betta into the tank.
Edit: It might be a good idea to:
1- put a big sign above yor fish tank that says : "DO NOT TOUCH"
2- Place your stuff where the cat wont sit on it. I like to put all my stuff in a deep skinny container lined with paper towels.
Last edited by aokashi; 08-31-2012 at 12:19 AM.