So my angry mood was spoiled by being intercepted by more people than I thought would be there before the meeting.
Instead, I played up the sadness. I acted very morose. Immediately had them asking if I was alright; that I seemed depressed. Played that out for the next half hour; stayed distant, outside the room, like I couldn't be around anyone. Then gave my speech about deciding to disband the club, apparently quite convincingly. They were pretty much speechless. As I closed the door, one of the girls pointed out it was April Fool's Day and they erupted in laughter. All went well if you ask me.