Jereberly, I have to agree with katiekate here - taking away someone's right to decide to not drink is not prank material, it is seriously wrong. It sounds like you and your friends are young and that there likely was no ill intent here, but nonetheless, there were obviously some pretty serious consequences.
That being said, he will have to decide his own course here going forward. You can't make him not drink. He was trying by taking antabuse - I'm not sure I can say that the antabuse in & of itself is a full sobriety/recovery plan, but it sounds like he was trying. You were there at the cafe today but you can't be there to pull a drink out of his hands every time. You will need to ask yourself whether you're willing to put up with the trials and tribulations that come with having a loved one who is an alcoholic, and he will have to decide on whether he wants to work on his sobriety.