Ex issues

My boyfriends ex keeps flirting,touching and talking to him all the time.thats what she does in school to other people's boyfriends I told my boyfriend that I didn't like it and he keeps saying there's nothing he can do about it.i get so jealous when I see them together or someone tells me they were saw together I think I need a break from him and if he doesn't do something about this problem am gonna break up with him even though I love him so much.did I make a right decision?