Why is my son hurting his brother

[whoopstheregomyinsides]

My 12 year old is being awful to his 7 year old brother. It’s been low level fighting but seems to be constant and I feel like he’s bullying and getting worse.
He is always clipping him round the head, knocking him over, pushing him, grabbing him, tripping him and is verbally nasty to him too. And then he’ll be lovely with him. Help him on Xbox and allow him to play with his friends. And then boom! Starts being horrible. Calls him fat, stupid, rubbish. Is awful about his skills and it’s so wearing
He says electronics ban doesn’t work (but I’m still enforcing one(. He’s fabulous when he’s nice but horrible when he’s not. He’s much bigger physically than his brother and getting bigger than me. I need to stop it but I’m also fretting there’s something wrong with him making him behave this way.
Tonight he hit him while he was eating and his brother scalded himself with hot food that was knocked onto his arm by the hitting. I’ve had enough. I suffer with anxiety and feel like a shit patent and want to protect my thoughtful, kind, loving son and retrieve my older son from this pre teen nasty shell he appears to be inhabiting.
Anyone else?

[JiltedJohnsJulie]

Really sorry OP, I have no answers to this but if you ask MNHQ to move your thread to the teenager section, you might get a few more replies (hopefully)