I have a birthday trauma like this and celebrate my half birthdays instead. My birthday is a quiet day for reflection. It works for me. Could you get people to do that?

I'm so sorry, OP. This sounds incredibly hard.

I get it OP but you have to use your words.

OP for yourself maybe you should treat your birthday as a day of remembrance fo your twin. You can mention this to close friends and family.
Then have the next day, or a week later, as a celebration for you, where you celebrate your birth and life