My boyfriend tried to kill himself! Please help!!!

Last night, my boyfriend tried to kill himself. If you can help me in anyway please do. I cant stand watching him try to kill himself. I'm pregnant, and he's the father. I'm wandering if he doesnt want this. If I could understand why he's acting like this, then I'd be so happy. He seems happy enough when we're together, but last night he tried. We were sitting in his room, listening to music, and he cut himself. If I hadnt stopped him he would have stabbed himself. I'm so worried about him....