My boyfriend is a drug addict

My boyfriend is a drug addict. He's lies to me & manipulates me about drugs. I've never seen an addiction like this in my life. We have a 5 month old son and I really can't do it anymore. He'a never happy unless he has drugs, this particular drug makes him seize, throw up, twitch, yell, and just trip out. He is a great dad when he doesn't have drugs and I love him so much but he just doesn't care anymore. He wants drugs and thinks it's okay. Like he genuinely sees nothing wrong with it. It has affected his brain and his whole outlook on life. He has gone to jail, and mental hospitals. Nothing helps. He refuses to go to rehab but I don't think it would help.. I have officially lost all hope. I just want to die. My son deserves better parents than a drug addict and someone who can't let go of that drug addict. I really can't. I have tried and tried to leave. Never go through with it. I really just am tired of life at this point. I'm tired of being stressed, worried; and feeling just not enough and unloved. My baby boy deserves the world and I can't give it to him. And about my boyfriend.. It's more than the fact that hes the daddy, I love him. But I want to die because of him. Because of him, I hate my life and I can't even be strong for my son. I just want to die. I hate this. I hate my life. I want my son to grow up in a happy loving environment and this isn't it. Now I see no light at the end of the tunnel.. I'm all alone, but I guess I've always been all alone.