I dun hv the courage to say break up because he want to kill himself.?

i and my boyfriend had been quarreling so far.. we had talk about break up. Whenever i ask for a break up he will say he will kill himself if i break up with him. so what should i do? but untill now i really don't dare to say break up.. really worry that he may kill himself..i really want to end this relationship. i'm tired..