So my 9yr old DS has ADHD and autism, so his behaviour isn't always the best. This week however has taken the absolute piss. He has punched my OH in the face (not dad) during a telling off, and then tonight has set fire to his brand new bed/mattress with a lighter pilfered from a high shelf in my bedroom (no idea how he reached it). Not going to lie, I absolutely lost my shit with him, I screamed at him that he could have burnt the house down, and I called him an idiot. He's very defiant, saying he's going to tell the school I screamed at him, and that u hit him (not true). How on earth do I handle this??