Constant feeling of being a bad person

No matter the situation I'm in, even if I'm the happiest in the world, I have this lurking feeling I'm a bad person.

I always say the wrong things and idk if I'm using autism as an excuse or a cause.

I don't want to be a bad person. I never intend on hurting others. But I always do by accident. How can I be better if I don't know how to be better?