So I 19F, found out my sister 25F was going to Houston for the BTS concert a few weeks ago. Her friend had already bought the tickets in December and there was no way of returning them. I didn't really care about BTS but I told her I wanted to go to Houston with some friends for a graduation trip to the spacecenter. After talking with my mom, she convinced me that it would be ok of she went but I made her promise she wouldn't go to the space center, the only place in the world I wanted to go.

Sadly in January my close friend passed away, the one who I wanted to go to the trip with. I admit that since I was in grief I was angry and sad. In March I find out that not only did she go, SHE ALSO WENT TO THE FREAKING SPACE CENTER! I confront my mom about why she did this and she says that since she's going to Houston once in her life, she should go to the space center. And that other people go to Houston so it's not a big deal.

I felt hurt and betrayed because I thought they would at least keep this promise to me, especially since I'm hurting enough as it is. I haven't spoken to my sister since and she thinks it's just a big joke. My mom is asking me to go talk to her but I don't see why I should. AITA for keeping this grudge? I need a third opinion because all my emotions feel heightened.

BTW this is a throwaway account. For context she has seen BTS perform before and since she's older she's gone on plenty of trips before. I don't see why this needed to happen, especially since she had to lie to her workplace just to go.