No Children At Baby Shower

My mother, sisters, friends and I had a Baby Shower planning session today. This is my first baby, and the only baby shower I ever plan on having. I was planning on doing it myself (I'm a bit of a control freak when it comes to stuff like this), but they're all insisting they want to help. So, I mentioned that I don't want any kids there (kind of like a kids-free wedding), and my best friend about had a fit. She said that her daughters (my Goddaughters) who are 3 & 5 will be devastated. I told her that I didn't care. Am I being too harsh? I just want everything to go the way I want it to, and not have tons of screaming kids around!