If you have to stay in and white knuckle it to get through day one then that's what you have to do! If you are no stranger to sobriety you know it gets easier. Try to remember that. Also maybe try to be "the observer" , the person watching the person. Observe your craving, let it wash over you, and watch how it eventually just fades and disappears. You can do this! We are all rooting for you!