What is wrong with my brother?

I'm 14 and he always tries to insult me mainly when we are at dinner or out at restaurants. For example when we out at a restaurant, We are on holiday in California and I planned some things to do and he said yeah, you're stupid. I said I'm sorry I took an initiative and he said. It's not initiative it's just google. I said at least I tried and he said yeah first time for that. He will tell us to shut up (with swearing) when we talk too loud. Recently because I have an insecurity about using bathrooms he said you're weird and said I'm going to embarass you and walked in to the other room and started saying She can't use the toilet, she can't use the toilet. He always insults me and my parents and just called my mum stubby and fat because of the pants. He called me a wizard and insulted me because I answered questions quickly. He always tries to put the blame on me. I asked him if he was jealous honestly. And he said to my mum..Look at her honestly why would ANYONE be jealous of HER. He is really frustrating me and I can't take it anymore. I'm try to get on with this but he keeps saying that it's me now and I don't like this.