He's crying and I can't stop laughing.
Did you think this would be funny?
No, I wasn't. I thought the film was a sad one.
I hope you enjoyed the movie. It's okay that you had a different reaction to the movie as your friend. Just understand that his reaction is a valid one also.
I really hope I don't get murdered after this.
Why would you get murdered? Just talk to you friend, explain that you weren't trying to make fun of him, you just thought the movie was funny and not sad.