My ex bestfriend has invited me to her 21st dinner at the end of the month..

I think the only reason why she's invited me is because she came to my birthday drinks and we hung out for a few hours and she said that i should go to her birthday dinner and to be polite i said yeah maybe.

I have made it clear that we can't be friends but we were best friends for 8 years and i feel honored that she has invited me.

But what do you ladies think i should do?