i feel like dying

They always say when you hit the lowest point, the only way to go is up, it cant get any worse.
First I am sure you are not that worst type of man, and dying certainly wont change shit. It will just destroy your chance to change, your chance to show others what you are capable of. Humans have the power to change as long as we have the desire to. One step at a time.
Why not first try going to the gym or just workout at home? it will definitely give you some confidence and a goal. After that it will spiral up.

And you said if you die, life would be brighter for everyone? did you do something to the people around you?