why do guys have to be such jerks to you?:(

every year that I have run into my cousins best friend he has put his arm around me in front of guys that like me and in front of guys I like ill walk away as soon as he does but im always scared of what he tell the guys after I leave cause he never tells me what he said. he does everything but scream to the world that he basically likes I me and im flatered and everything we were friends until he got possive and now he turns everyone against me. the only people who stand behind me are my 17 year old brother and all his friends who practically rule the campground where I see my cousins friend every weekend starting in may. and I dread the day that my parents shove me in tyhe car and drive us up there cause I know that like every other year hel be my friend get possive ill tell him to stop and hell ruin me so I go almost crying to my brother and his friends who can only tell this guy of without getting in trouble.I hate it and im always losing the friends I bring with me cause he makes it seem like I lead him on. I’ve just patched things up with them but now when my cousins viste they always have something to say from him how sorry or whatever. and once again I hate it no one can help me without turning against me it happens every year for 5 months . sorry if this is long but I could really use some advice what should I do???