My friend I have been where you're at, overwhelmed by anxiety, fear, shame, guilt. The first thing to say is that you've made the right decision to stop and believe me the withdrawal symptoms will go away with time. You won't look back and laugh but you will look back and be grateful that you came to your senses, life gets so much better with sobriety. For now just focus on staying sober, everything else will begin falling into place as long as you keep up the sobriety. All your anxieties about the program will seem much much smaller in sobriety, trust me!