How Can I Make My Mum Split Up With Her Boyfriend?

I'm only 13 and he picks on me.He gives me dirty looks all the time,trys to make me jealous by kissing and hugging my mum infront of me and then smirking-he screams and shouts at me for things like,forgetting to shut my bedroom door-i get severly punished by him just for that,he also calls me names(dumb blonde)(ugly ****).I have tryed to talk to my mum about this but she dosnt believe me.Any help would be great,im too scared to call childline lol- i don't want to be taken away,x