You should DEFINITELY have the "victim"--the person receiving the money--sign a release; and, in fact, you should NOT pay anything without getting a release; otherwise, they could take  your money and then sue you anyway! (This is a good rule of thumb; whenever you pay money for any reason, get something in writing delineating what you get in return, whether it be a release from a debt or liability, or some affirmative service.)You could likely find some model or template from the internet by Googling (or the equivalent) "car accident release" and similar searches. (We can't recommend a specific form to you, unfortunately.) However, you would be much better off having an attorney create a release for you--as well as generally review the situation and your response--to make sure you are full protecting yourself from liability. Good luck.