Severe depression, what can I do? advice please!?

i am so sad all the time, not happy with my life at all, I am severly overweight I weigh like 330 pounds, I am not happy with my relationship with my man, I live with my mom and I need change, I didnt gradute highschool and I am so depress I cry all the time and I am very nervous around others, I just dont know what to do, please help!