Guys bully me, im a girl and they have made my life hell?

I try being strong and i feel it in front of them but then i get home and burst into tears. They dont know i do but its getting worse. I store all my feelings up in front of them and then it alls comes out when im alone. I try telling my friends but they get it too. We try to help each other out but its not working. How do you stand up to a bully whos a guy.