Though I have no experience with a loved one being in detox, all I can say is this:
Step away from the alkie and give him the dignity of finding recovery himself. By attempting to intervene, help (manipulate), you rob him of that dignity. Furthermore, there's nothing you can do or say (or not do or not say) that can prevent a relapse.
Focus on yourself, go to Al-Anon and let HP stear this rig.