Kind of a silly question...?

I am 22 years old, and my boyfriend is living with me. We also live with my parents in their house. Lately, i've been feeling kind of afraid of my boyfriend. His is getting angry over everything, and talks about killing people a lot... now, i know the obvious thing here is "get out of there" or "kick him out." However, he knows where I live, and i'm afraid he might come back if i piss him off. I do love him, i just wish he would stop being so angry all the time. He even mentions killing my step-dad every now and then, and talks about murdering people all the time with the multitude of guns he owns. None of these guns are in this house, but that doesn't mean he can't go get them. I guess i'm just freaked out. I just need an idea of what to do, hopefully someone knows ways i can save this relationship.