What can I do if I am being sued for an accident that I couldn't help?

It's almost 10 at night and it is raining outside. I'm driving down a steep hill and there are two cars in front of me. The one in front slams on his brakes so the car in front of me hit his brakes. He barely stops before he hits the car in the very front. I hit my brakes all 4 wheels locked up and I started sliding right into the rear end of the car in front of me. The driver was a big over 300 pound guy with the seat reclined all the way back. I had no insurance at the time and my car took all the damage but yet I'm getting sued for $16,200.00. What do I do!? I've requested all known pictures and reports and also all documents so I'm waiting on all that to come in the mail. Other then that I don't know what to do.