Budgie, I totally agree with people have said. As your friend, she should understand you don't want to do anything you're uncomfortable with! It's not as if you were purposefully avoiding her. You agreed to do things with her that you were comfortable with and that you could still see her. She can't say she wants to do different things and have people jump in/out of them if she's going to be upset people don't want to do it all! That's completely unreasonable of her!
I did something similar for a joint Halloween party I had two years back. I made it so people could come to a haunted house late after the party. It was $18 per attraction or $40 for all six. While only my boyfriend and I could afford them, it seemed none of the 12 people we invited there could go and instead of just leaving them all as the hosts of the party, we just changed plans because we understood our friends have tighter budgets than we do and that's what friends do. They understand, "Oh, okay. This doesn't work for you for whatever reasons and that's okay!"
When she had said she was making it into parts I was revealed, because I thought I could not go clubbing and not hurt her feelings - but she's still taken this as some sort of insult :/ and her attitude is making me not want to go at all, which would be a shame We'll have to see when she starts talking to me again >.<
I had a somewhat similar problem for my sister's bachelorette party.
I too don't enjoy clubs/partying, but the other part of the equation was that I needed to bring Aurora with - she was only 4 months old, and exclusively breastfed (never had a bottle). My sister was MAD about her coming with, but we had a day-long thing where we went out for lunch and then had a scavenger hunt at a mall during the day, so she was with for all of that, and then we went to a piano bar for dueling pianos around supper time. I brought Cole's teenage cousin with all day (for the lunch & mall portion too) and then she stayed with Aurora at the hotel while I went with to the piano bar for a little while. I told her to call me as soon as Aurora was unhappy - I'd rather leave after 15 minutes than have a crying baby back at the hotel. I was at the piano bar for about 40 minutes before needing to go back to the hotel for Aurora. (I had given my sister the option of me not coming at all, and promised that I wouldn't have hurt feelings if that was what she chose, but just basically said that my options were to bring Aurora with or not to come at all, and I was fine with whichever she wanted)
SO, sister was mad before the bachelorette party about: A) Aurora coming with B) Becky (babysitter/cousin) coming with C) me leaving early
But she was gracious and friendly the day of the bachelorette party, and thanked me for coming. I think looking back now, she realizes it wasn't as big a deal as it was seeming to her at the time - wedding planning is stressful and every little thing seems SO BIG - and then their wedding day is over in a flash and they can take a step back and see that it wasn't such a major thing. It will pale in comparison to the wonderful special memories with her wedding.
That long story is meant to say that I think you should go ahead and do the portion of the day that you're comfortable with, and just overapologize if you feel like you need to: "I'm really sorry you're disappointed, but this is what I am comfortable doing, and I really want to spend this time with you". She may be upset about it beforehand, and even the day of when it comes time for you to leave, but I think/hope/expect that down the road, she'll be over it and just be thankful that you were able to come at all.