Question about my children and my ex?

Ok so my ex wife and I have two young children together. An 8 year old daughter and 2 year old son. They were both invited to the wedding which is fine and I allowed them to go over to her house tonight and spend the night so they could go to the wedding tomorrow. Now I have them for a week and my ex has them for a week and this week is my week but I told her they could go to the wedding and I would pick them up after the wedding. My ex is now b*tching at me because I want to pick them up before the reception. There is going to be lots of drinking at the reception and I do not wish for my young children to be around alcohol. I am just trying to protect them. I know there will be some people getting drunk, one of my best dudes will be there and will probably get drunk or buzzed at least and I really don't like the idea of my children being around alcohol. My best dudes wife is my ex's sister and she took Jae (my 8 year old) for the night so I went and picked her up from their house and am outside my ex's house waiting to get my son. I told my ex that if she was going to throw a fit about them not going to the reception that they didn't need to go to the wedding at all. Is that fair? And is she being fair? All I ask is that my children not be around the drinking and alcohol. Not only that but they would get bored really fast being that there isn't anything for them to do at the wedding or reception. She is being a complete b*tch to me right now. I just don't know what to do. Any help is appreciated. Thanks.