My boyfriend has depression

There isn't a day this past month that he hasn't said he wanted to kill him self and or die. I don't know what to do, I'm horrible when it comes to comforting someone. He's also so very negative all the time...it used to not be like this. Not as bad at least and he's slowly getting worse and worse over time. He refuses help, and how am I supposed to respond to him saying he wants to die everyday? All I can say is I'm sorry, or I love you but that never feels like it's enough. Every time I ask him to talk about it or what's wrong he never has an answer. It's gotten to the point where I feel emotionally drained by him. I love him, but the love doesn't feel as passionate anymore. And I'm starting to feel more and more guilty because I've thought about other options, and possibly breaking up with him because I want to be with someone who isn't so gloomy, but I feel like I'm the only thing that's keeping him going. I don't know what to do.