Since he appears to be a whiny little bit** anyway try this.
"Oh my God, what have I done? I'm so sorry that I killed you "insert characters name". IF ONLY I HAD KNOWN!!!!! OH THE HUMANITY!!!! I will spend the rest of my life atoning for this horrible mischance!" Then smile at him, munch some popcorn, and watch him have an aneurism. Fun for all!
Seriously though, you did nothing wrong and he needs to put on his big boy pants and roll up a new character.
