I'm not footing the bill for my friend's bachelorette party.
Why wouldn't you pay?
I don't like her anymore, and I don't want to see her again.
Why would you be in a position to pay for her party if you don't like her. There's no reason for you to even go.
Yes, I do. I'll have to see her often.
If for some reason you have to see her on the regular it might be nice of you to pay a little if for some reason you are expected to.