now what?

I type tonight furious. My older children pulled such a mean and nasty stunt on their little brother. I could hear the 2 yr old screaming, not "I'm not ready to go to sleep" screaming but "somethings very wrong" screaming. The short version is that the older boys told him that the statue of liberty had come to our house and killed our dog. I can't get a straight answer as to which one told him that. I have never ever seen JJ so distraught! His face was bright red, and he was sobbing as he screamed, "Doggie! Doggie! Doggie, ok? Doggie dead?" I handed him off to Daddy to show him that the dog was indeed alive and perfectly fine. Then I lost it. I yelled. Maybe I shouldn't have yelled, probably better ways to handle it but yet I yelled. I informed the older boys that there WILL be consequences and big ones at that but that I was too angry at that exact moment to be able to discipline out of love not anger and that we would discuss consequences in the morning. It took over 10 min to calm JJ down. Tears spilled out of his eyes and every time we got out of sight of the dog, he cried again, "Doggie? Mommy, Doggie!" (The dog didn't seem to mind, he got a milkbone and a treat during the process of calming JJ down!) I finally got him reassured the Jack is alive and going to be here in the morning when he wakes up but he still seemed rather unconvinced when I laid him down. His brothers were smart to not talk when I brought JJ back to bed. I could see that they were still awake, but they were pretending to be asleep which was better than what they had been doing for the last 2 hours before that. And now I am left to ponder the consequence. I contemplated taking away the play date at the park with a friend tomorrow, but my hubby said it wasn't fair to the other kid who is already looking forward to it. We could do the usual, take away sweets or tv privileges. Somehow though the usual consequences don't seem like they will convey the seriousness of the situation. How then do you discipline when you are out of ideas? How do you teach your kids to not be cruel to others? What they did tonight, crossed over the line of not being nice into being cruel. And they just don't get it! My oldest told me today that it was ok for them to be mean to another little girl. Will said that the golden rule said so. HUH? "Well, she hasn't always been nice to us so that must be how she wants to be treated so it is ok to be mean." Now what? How do I guide them on this one? I don't want an ordinary consequence, I want them to learn the lesson. The problem is that I have absolutely no earthy idea of how to teach it! So tonight I pray for wisdom and guidance, I blog to get the feelings out and I ask if any of you have any ideas. Help?