This is concerning DS (9) and three other friends. Backstory:
DS has always been good friends with them all, but one of them, let's call him Martin, got a bit possessive with Joe and fell out with ds and Fiona about it (didn't like the fact that Joe was friends with ds and Fiona).
Recently, Martin went to Joe's house and they both got into making potions. It later transpired, that Martin was making a potion with the intent of putting it in Fiona's water bottle at school. He had pissed into the potion as well as mashing up some poisonous berries in there (from Martin's garden, whose mum had warned them not to go near).
Now Martin has sent a christmas card to Joe with the following message:
"I wish you a very Merry Christmas. May it bring you joy, happiness and everything else you deserve especially to assassinate DS and mostly Fiona."
He has drawn a picture of a sword dripping with blood with the caption "Fiona's and Ds' blood".
I'm finding this unacceptable. AIBU to want to talk to the school or his parents about it?