If you are serious, all i can say is don't panic!
However, you must realize that 90% believe this stock will go down before it hits a realistic bottom and begins a realistic growth trend.
You can be hard line and believe that it goes up from here, "hold" or you can bail and buy back latter at a lower price if you feel you need this stock. Hence, take a hit now and try to recoup latter.
$24.50 is kind of high considering most recent price action. In other words, i see it going lower before it reaches this level, even given the occasional short squeeze.
$24.5, well after today, i cant see it rebounding to that level for a while.
If you have the financial strength and can take the hit, do it and learn a lesson. If you must, buy FB back later when it hits the bottom, many say mid- low teens....
If you decide to sell, wait for a rally and get out. Move on and learn from your mistakes.
To make it hurt less, just sell off a little at a time when the price rises, then if a high act of God happens, your still in.
Thats just my opinion, i am not an expert but fairly successful at this.