Parents bitter about us not wanting to make plans with them on our anniversary?

Husband and I just had baby, we never get time to ourselves. Parents live an hour away. It’s our anniversary, we made plans with parents a while back, for them to watch the baby while we go to an expensive hotel and celebrate our anniversary. Well now, my mom is trying to throw in that we need to have lunch with her and my step dad either today or tomorrow. We said today is fine, we’ll that now doesn’t work for her. She wants us all to have lunch with them “at the club” which is like a 2 hour ordeal, and this would be on the day of our anniversary. I said no, because it’s our anniversary, we were hoping for them to just watch the baby.. well now she’s upset saying that it just seems we want her to watch the baby, we’re kind of using them type thing.. well duh, that was the plan so hubby and I could celebrate our anniversary. My mom is mad now, and now it seems our plans might fall through and we are going to have to bring the baby with us. Anyone have any advice? Am I being a brat here?