Do you think a step-mom should have checked with Moms of the New Mom & Dad before planning a baby shower?

My son's step mom planned a shower before checking with me or the other mom. She is going to "allow" me to help if I want. This is a woman who hardly knows my daughter-in-law. She is inviting everyone, so will be on one left to invite to mind. My son lived with me & only visited his dad, I was the stay at home PTA mom, I have done everything for my son, never bad mouthed his dad, there was a lot I could have said! They have made up stories about me & told my son! I would just tell him I didn't do whatever studid thing they came up with, it never worked, my son still wanted to be with me and never wanted to go live with them. My husband was a better father and provider that my son's dad, he is the one my son looks up too. Whenever the step mom is around other people she is nice to me, but asks like I am the step mom, when people are not looking she is evil! I just smile and take it, I though I was done with them. I am so sick of her! FYI her child is in prison!