I agree with aaron about letting your renters insurance company handle the situation.
Are you sure that the faucet is where the problem came from? Could it be that the water heater has reached the end of its life and is now leaking? It also sounds like the water heater may have been installed improperly if there was no provision for catching a leak, as this is what water heaters often do when they they go bad. This may also mitigate your negligence to some extent if some how you are liable because you or someone you control (family or guests) opened or damaged the valve. Again, renters insurance will help you sort this out. But if wait too long to put in a claim, you may not be covered, and this is what you got yoour insurance for.

