Am I liable?

What is the name of your state? California

I made an illegal u-turn and did not have ample space to complete it so I put the car into reverse and proceeded. A van stopped so that I could adjust myself and another car stopped behind it. A truck then hit the car which then hit the van. I was not hit in the accident, am I liable for the damages?

Possibly. We weren't there to see it so no one will be able to say for sure. Why not let your insurance company worry about it if you get sued?