baby shower

My MIL planned and bought everything for my baby shower without my moms help and when I confronted her about it, she said the only thing left to pay for is food. The food is already taken care of by the god father. I'm so upset about this. I'm trying to remain calm but I really feel like flipping out. My MIL already has 10 grandchildren. This is my moms first grandchild. She knew up front that my mom was to be included!!!!! My mom went and bought all the decor, plates, napkins, etc and is being told to just take them back. My MIL picked the place, the cake, the decorations, the favors, and had HER daughter in law do the games. She is not my family!!! My mom means more to me than this baby shower does and I'm so ready to just tell them to cancel it. I'm upset that there's even drama! My boyfriend sided with his mom and said that me and my mom wait until last minute to do things and it's our fault. My mom and I have found ideas way in advance that she was going to do. she bought some stuff last week. My MIL bought her stuff yesterday. What would anyone else do in this situation?