It hard to even comprehend that anyone would be 'better off' without the people they love. You should try to have a little more faith in your friend .. Sounds like your friend places a lot of faith in you.
You want advise .. Then be pro active. Don't wallow in self pity and stop focusing on sabotaging your support system.
If .. And I'm not even going to commit to saying you do .. IF .. You really do have depression .. And I mean clinical depession .. Then the best advise one could give you is to get help. Talk to your doctor. Clnical depression is more than just feeling depressed .. It is a chemical imbalance in the brain that can be treated.