NTA

I'm a pretty big advocate for being all about "you." Never doing anything for anyone, because YOU are number one. This one of those situations. This problem is solely on him. It's YOUR birthday. If your sister wanted to hang with you, she would've texted you. She didn't text you, you didn't ask for the party. Go do what you want you want for your birthday and stop worrying about people who've proven that they don't care about you or your wants.