Suicidal brother? Please read whole thing.

If I'm being totally honest, I don't think he's actually suicidal and I think he does a lot of the things he does to get a reaction from me. We're very close. I'm 22 and he's 20. I actually suffer from depression and anxiety that I recently started taking Zoloft for so I don't take mental illness lightly at all. My brother often gets spontaneously anger, especially since he was fired, and says things like "I'd be better off dead" or "maybe I have cancer and will only have six months to live." I give him advice and pep talks and ask him if he wants to talk, but he would rather throw his phone or punch a wall or go on a rant about how terrible everything is than think rationally. I try so hard to be supportive but it's hard because he says really cruel things to me. Like one second he was fine, and then the next he randomly says to me "you're a nuisance to the whole world" because I needed to use the electrical outlet. I laughed it off and playfully said, "no you're a nuisance." And he gets angry and says I'm going to feel sorry when he dies in six months. He then proceeds to ask me if I would stop him if he started to suffocate himself with a pillow. Idk how to handle this.