How to deal with him being suicidal?

My ex boyfriend who i'm still very close to is always threatening me with "I'm going to kill myself." I don't know how to handle it. He cuts and burns himself. He overdosed last month and ended up in ICU. They let him out but he still abuses drugs (pills) but no one does anything about it. He texts me every night saying hes going to kill himself and he loves me and goodbye. I love him so much, but it makes me want to hate him and just never speak to him again because i hate living with the fear that he's going to kill himself and i'm the last person to talk to him, and I couldn't save him. Sometimes i just say whatever! bc it makes me so angry. I don't know why he does this to me. I told him how much he means to be and how id be so incredibaly lost without him. He drags me down with him and has me so depressed. Every little thing I say he turns it around and tries to make me feel bad for him. I thought he only wants attention, but he's actually attempted suicide before. It doesnt matter if i tell a school councilor or anyone because when they put him "away" hes sooo much worse when he gets out! Tey cant help, i'm the only person here for him, his parents died. We're all each other has and i dont want to loose him. What should i say to him when he says this to me, please someone help!