It's my friend's birthday soon, but I'm not gonna spend time with her for it.
She's your friend! Why would you abandon her on her birthday?
She's really annoying right now because she's hungover. I need to teach her a lesson about drinking.
Friends who drink can be very hard to handle. It is her birthday and that is a special occasion for her, don't abandon her on that day. She will never forgive you and you will lose her as a friend.
She can handle the hangover. She has them all the time.
Regardless of how often she drinks, she is still your friend and you should be there to celebrate her birthday with her. If you don't show up, she will be hurt and confused.