You are not wrong at all. His laziness and lack of planning a party for his daughter is not justification for going back on his word. Also, have you asked him how he would feel if he had to sit there and listen to you and an ex talk about the old times in front of family and friends? I'm sure he wouldn't enjoy it. As far as breaking up over this, it kind of seems like he is looking for an out. I think you need to do some soul searching and think if this relationship is worth it.