SO mom has gone crazy

So yesterday my SO Mom decided to text me talking about the baby shower. She has picked a theme, time, date and the location without talking to either of us or my mom. I️ understand she’s excited but she has honestly crossed the line. This is not her shower but that’s how’s she acting. How do you plan everything for someone without telling them what is going on. So we finally confronted her about it and then she got mad?! I️ don’t understand her way of thinking at all. First she was gonna throw a shower for him and just him and I️ was suppose to throw my own🙃.. who’s wants or would go to two baby showers?! But she didn’t understand that at all. Am I️ wrong for being upset?