My body is dying

Well my depression is effecting me a lot. I feel that my body is dying: I have stomach pain, pain in my shoulders, low heart beat, dizziness. For the first time of my life I actually believe that sadness can kill you. I also knew this week that my best friend was hospitalized for 2 month for being anorexic and was going to die. I feel so sad because if I loose her I literally kill myself. I want to help her and let her out of this but I can't even help myself. I am really obsessed about my weight and I can't continue fighting because food has been so comforting for the past 8 month. I don't know what to do...