Hi Loveisallyouneed. I can understand how fearful you are, but I really believe this will be a wonderful experience for you. You will learn tools and won't have to resort to white knuckling to keep your sobriety.
You're young and your body will surely have the resilience of youth to heal from physical damage. Your treatment will help the emotional part and will probably help the physical part as well.
I know what you mean about caring for yourself, and then again, not caring for yourself. I had a couple of times where I didn't care about myself, thinking, "What's the point?". I posted here first and the fabulously caring folks here talked me out of taking that first drink. SR is a major part of my plan.
My experience in taking that first drink would be similar to GettingCloser's. I'm not a chugger, but I would steadily keep drinking.
You are going to have an awesome experience. This is not a punishment....this is a gift. You've done superbly already at 20 days. Hang in there. Be strong.