WHAT SHOULD I BELEIVE??? betta and tetra help.?

in my life i have had 3 bettas. 2 of them were boys and the other a girl. i also have tetras. every fish BUT the tetras try to eat the beta (even the girl ate the guy) and the tetras didnt bother the beta one bit. the kinda like split the tank in half but didnt hurt each other. i think u will be safe....... if the tetras do die its probally cuz they ate each other not the beta