I spilled water on my mac.

@aurmazing time to disconnect the power. Disconnect your power supply and your battery MacBook Pro 13" Unibody Mid 2012 Battery Replacement

After that you will have to treat it as you would any other water immersed device.

For now you want to stop using your computer. This potentially can make a bad situation worse.This may further damage your MacBook.

The next thing to do is to clean it. Disassemble your computer using these guides . You must remove all EMI shields from your logic board. After you removed those, clean the whole board, connectors and all with +90% isopropyl alcohol (higher grade if you can get it). Follow this guide , and even so it was written for an iPhone, all the points are still pertinent to your MacBook. While you clean your board, check for any obvious damage, like burned or missing components etc. All these steps are to avoid delayed failure caused by corrosion. Best thing to do would be to clean it with an ultrasonic cleaner, but if you do not have access to one, this will at least help. You also want to make sure you clean the MagSafe DC-in board. Once all this is done, reassemble your MacBook and reevaluate. Let us know how it works out and if there are any residual issues with your computer. Until it is cleaned, everything will only be a guess.