I'm going to get angry at my friend for splitting the bill on her bday party
What are you going to do about her charging you on the bill?
I'm going to say something bad about her because I didn't want to pay for her.
You have every right to get angry at your friend but it's her birthday and if she wants to split the bill you need to pay your share. Your friends will all think you're selfish if you get stingy right now.
You can share your opinions with someone else. I am not paying for anything.
I understand that you don't want to pay, but this isn't my opinion and I'm just telling you how they will feel. No one wants a friend who won't help out for someone's birthday dinner.