My stepmom made a rude comment about my sister’s hobby in front of me

Hello everyone, this happened the other day.

I do theater and my sister does sports, but specifically basketball right now. I was telling my stepmom about a show I had that night and she was excited but said she couldn’t go cuz my sister had a basketball game. Later before she left she said to me, “I’d much rather go to your thing than go to basketball.” Now she is allowed to not like basketball. In fact I myself am not a fan, and her not wanting to go but still going Is admirable. However that isn’t my issue, my issue is that she chose to tell me that. I honestly feel like I’m overreacting, but I feel that it is inappropriate of her to make that kind of comment to me about my sister in front of me. I also feel that a reason why this has me so upset is that our stepmom loves to gossip and talk crap a lot. If you tell her something most of the time she will tell others, and this bothers my sister and I. We have tried to talk to our dad about issues in the past but we get shut down or it’s not even acknowledged. Another reason I’m upset is that is our mom (who died many years ago) I feel would not be happy with that kind of comment about her daughter, and the final reason I’m upset is cuz of the roles were reversed I would of been be upset to know that she said that about me. So yeah, I don’t think I’m gonna cause a fuss about as I’m tryin to move out anyways but I want to know I I’m justified or if anyone agrees or disagrees with me