hey, thats a pretty tough situation, all i can suggest is taking your dad to one side, you say hes the weaker one, hes more likely to believe you. what you should do is sit with him and tell him everything, how you feel and stuff and even if you have to start crying to make him understand, do it. and tell him you cant cope with how it is anymore, hopefully he will understand your situation and try and stand up to your mum by telling her, i know your mums tough and doesnt believe you, but if the dad thing doesnt work, maybe trying it with her might help a bit. i know how horrible and annoying brothers can be, i have a 12 year old brother but if i go to hit him he smacks me back and hes alot bigger than me even though im 18 lol. but its worth a try. in my opinion your brothers are more to blame than you, i would of roughly handled him too given the situation. hope this helps, if not im not sure what to do other than keep out of everything they do