Is this mean tell me please?

i'm 16 and have a 14 year old sister called megan and about a year ago she fell for a guy my age called jamie and me being the defensive big brother i warned him to stay away and he done that then 2 weeks ago she said she fell for a 5 ft **** who bully's her friends away from her . any way i went down to her school to see him. I didn't like him so i said i'd prefer if she went out with jamie because he is respectful to me and her . when the little runt herad what i said he went to walk off but as i turned my back to him he picked up a rock and threw it and hit the back my head ,spat at me . so i caught and did a little damage of my own , now she still wants him and i want jamie to be with her .Am i wrong