I'm a freshman and need advice on help with a junior guy?

Alright, well I'm going to be a freshman this year in high school. Theres this boy who is a junior and hes going out with a senior. He says he likes me and wants to hu secretly with me. His older girlfriend found his texts to me and claims she will beat the **** out of me in school. I'm friends with most junior girls though and they said if she touches me they'll hurt her. I'm totally not slutty though and i really like this kid. i dont know what to do. he talks to me every night and dumped her once for me but i was sick that week and couldn't see him so he got back with her. i'm so confused and not sure on what to do because now he wants to try hu secretly again with me. pleasee help!