Crazy huge dude

Ok, my ex girlfriend is going out with this crazy-ingly huge muscled dude and he wants to kick my ass and I am puny and scared. So I need to know where and how I can get a knife that is small and how I can carry it around my body at all times as to use it in case of defense (and defense only!).

I'm seriously scared and hope you guys can tell me how I can do this?

Hard choice between gettinig your ass kicked and going to jail for stabbing some guy. Well if he doesn't take the knife from your weak ass and stab you with it. Your best bet was not to have gotten in to this situation.