And I feel nothing but fear and shame every time I give into it again.
It may be helpful, or prove beneficial for you, if you're somehow able to release yourself from the power that-that brings, when you do do that (every time you give in). Because, although it means so much for you to give it up, when you beat yourself up over having "failed," for lack of a better. I think, it just psychologically makes things that much worse (counterintuitive as it seems). For we are then even more apt, or likely, to go ahead & just do it again (later on). For we keep feeling defeated, as we've beaten ourselves down furhter and further. However, I also konw that it is not as simple as that. And that there is a lot more else that is (also) going on - in order to stop doing it. Just thinking this might be one thing you could do, if you can catch yourself, and try to reduce these sometimes overwhelming feelings, with that which may be in somewhat of your control. In spite of otherwise thinking (your), as a result of it being so behavior oritented (or just what you're used to doing: like a 'reflex.') Good luck with this either way/or no matter what!