Should I cancel plans to go to my sister's last minute bday dinner?

I’m 22 and my sister is turning 37 today. She never made any plans. I woke up to a text saying she has a birthday dinner tonight at 7:15 at a SEAFOOD place some place 40 minutes away.

First of all, I made plans today. Me and my boyfriend planned today at 6:30 to go costume shopping, zombie makeup testing, and a bunch of other stuff. I really hate that she did this last minute. I HATE sea food and it’s so far!!

>_<

I am most likely going to cancel plans just because I think all my other siblings are going…

Also the other dishes they have at the restaurant that are not SEAFOOD are steaks and it’s $20—$30. I can’t really afford that. I’m a broke 22 year old college student.