Struggling mum with 10 year old son

Hi, I would like to stay anonymous for the time being so I'll introduce myself as Mrs B! HI! So I'm a mum to two boys, 8 and 10! My 10 year old was diagnosed with autism and PDA at the age of 4, he was statemented and put in a school equipped to deal with his needs, after hitting all his targets of his statement he was put back into mainstream school, which he struggles with, bullying etc. He currently does ELSA in school to help with his emotions, he has recently told us he imagines his pen is a knife and he wants to stab people who are horrible to him.  little background on his family life, I am married (not to his father) his biological has been in and out of his life from day one, other than that he is part of a very loving family but he seems to be struggling a lot with his emotions, he's constantly angry and agitated even at things that aren't there sometimes. His brother just has to breathe the wrong way sometimes and he's so nasty to him. Were currently in the motions of moving to a bigger house so he can have his own space, we will do anything to try and help him, he takes things very literal, at the moment he says something from YouTube has taken over his body that is why he acts the way he does, in a very negative way like I said above about the knife  (YouTube is banned from the house at the moment) I guess I'm just asking for some advice, strategies, ideas anything! Have you been through it and come out the other end? It's  very hard to see a way out of this situation at the moment, we get no help from anywhere, CAMHS have told us it's puberty but have given no advice on how to deal with autism and puberty! Thank you for reading. I welcome any tips!