Wow, that's a pretty douchey move on your brother's part. I know time is valuable, but if you can't spend a little time with your family members for special occasions such as birthdays ... I hope that he has a legitimate excuse such as a work commitment. Hopefully you can spend the day with people who appreciate you. Happy Birthday, OP!
I don't want to eat the devils avocado, but maybe because he's really busy and isn't able to do so? Even if so he should find some time at a later date to hangout. Hope you have a nice birthday though OP!! c: