If you cancel the room, I don't think you should let him know. When at the wedding reception, don't talk to him unless he speaks to you, and then small talk. Try and be dancing as much as possible. Have fun.
Good luck.
Me:57 H:52 M:28 Got another lawyer last year and filed. D35,S/D twins28,D22 EA4/04 End? Who knows? "Life is like a mirror. Smile at it and it smiles back at you." — Peace Pilgrim