ASD meltdowns and no feelings

My son has not being diagnosed but are suggestions of ASD and ADHD. He his having frequent meltdowns, where his aim is to break me. When he is in a meltdown he said he has no feelings, he simply doesn’t care about anything. This eve he has trashed my bedroom, I have no control over him. Can anybody share anything on these meltdowns and having no feelings. When he is not having a meltdown, he is an absolute delight, really sensitive and really caring. So when he falls into a meltdown, I feel like I’ve been hit by a bus, as it is the complete opposite to his normal self,.