I've had some addiction counseling in the past and the therapist said that addiction is base on a cycle of thought; premise, action, confirmation.
It begins:
1 - I am bad so I do bad things (premise)
2 - Then we act out and do something we know is bad/wrong etc... (action)
3 - Our mind tells us, "see? you are bad!" (confirmation)
This is common in some fashion to addicts across the board.
Another thing common is a fear/punishment - cause/effect relationship between our acting out on the addiction and some perceived negative ramification...
This cycle is again; premise, action, confirmation.
1 - I do bad things (because I am bad - as above) so bad things will befall me (premise)
2 - then we act out and do bad things (action)
3 - Our mind tells us, "now, you will be severely punished" (confirmation)
It's something we all struggle with, in some form or another. It helps me tremendously to get it out in the open and see it for what it is: a negative thought pattern that is common to others with the same illness as me.
And the more we take it on together, the more we can overcome it!