What should I do if I think I am a bad friend
Why do you think you're a bad friend?
It is because I can't even invite my friends to my own wedding.
It sounds like you are aware, and regretful, about what makes you a bad friend. But have you considered talking to your best friends about this? They may understand your situation better than you think.
I don't need anyone's help. I'm my own man.
If you are aware that a certain action makes you a bad friend, you should avoid doing it. This will save you from being regretful in the future.