My best friend got angry at me because she found out I'm going to a concert next week. What should I do?

My best friend found out on Instagram that I'm going to a concert next week with my close friend. My close friend posted it. They don't know each other well. My close friends and I have been listening to this band for a few months. She texted me angry saying, "Why didn't you tell me you were going to a concert next week?!"
She doesn't even know this band. I told her about it and she said, "No never heard of them." I told her there is still time to get tickets but buy them online. She is like, "Whatever! It's too late now! My own best friend didn't even tell me. Why don't you tell me anything anymore?!" I was like, "You've never heard of them so how can you enjoy them? I'm sorry sis." She isn't responding. Wtf