Help with an intervention....?

okay, my family and i are getting ready to do an intervention for a family member that is an alcoholic. we have studied and researched best ways to conduct the intervention. our concern is his reaction. we are not sure what to do if he reacts badly. what do we do if he storms off angry? do we go after him, or let him be? we are prepared in most aspects of the situation. but any tips on what to do with his reaction or any other suggestions would be nice.