AIBU to not want to be a stand-in partner for my sister?

[babyfactoryclosed]

This may get a bit long but my DH came home early from work today (he usually works til 7or 8) to suprise me with a weekend away as he had just been paid for a biggish job.

The problem is that my neices 12th birthday is tomorrow and she is having a small party and we wont't be able to go now. Same child just had a huge party for her confirmation last weekend (which I helped organise). My DH didn't even know about the party as he usually works all day sat so he wouldn't usually go to anything on a sat.

I was delighted with having a weekend away just us and the DC's as DH has been working 10 hour days for months but when I rang my sister to tell her she totally freaked out screamed down the phone that I had ruined the party and hung up. Then she rang back to apologise but ended up screaming and ranting again.

She split up with her DH a few months ago and I have been acting as her chauffeur etc since then. I know she is now alone with her DC and its hard but can't I have some time to myself instead of taking her everywhere she wants to go for the weekend and doing stuff for her that her DH used to do?

AIBU to want to enjoy my weekend without feeling guilty even though I probably won't enjoy it now??

YANBU and it sounds like she doesn't really think you are either, but is panicking.

Just go and don't worry about it.

FWIW, I don't think you're being that unreasonable, though I don't think she's unreasonable to be disappointed either, given the late notice of your cancellation.

Is there not another family member she can get to help her, or a friend? If sh'es relying on you this heavily and it's wearing, perhaps it's time to start pulling away a little and getting her to stand on her own two feet - you don't want to be stuck looking after her forever.

You can't reasonably expect her to just be okay with you pulling out this time if until now you've given the appearance of being fine with the lift-giving etc., but I don't think it's wrong of you to want time to yourself. It's not your fault that this first opportunity for time off in months came up at the last minute either.

As someone with a DH that does crazy hours including every Saturday I am going to say YANBU.

DH has managed to get tomorrow off (first Saturday of the year) and it feels like such a luxury.

YANBU to want time to yourself, esp as you helped with last weekends party. You are not responsible for your sister and I think you should enjoy your weekend away and not feel guilty.

YANBU, I'm sure your sister is perfectly capable of sorting out a small party herself.

Have a lovely weekend.

Thank you so much for your replies.
Cat64 Sorry, I was upset and didn't explain things very clearly. She is not really having a party. She has just invited 8 kids to a soft play centre and she is bringing some party bags as she had a really big party last weekend. There are at least 3 other people that can drive her so that's not the problem. DH didn't even know about it as I just told him we were going to the soft play area with nieces and nephews. He booked the weekend away as a suprise for us.
I think the problem is that she always has me at hand to help her with everything and never does anything by herself. I know being a single parent is hard but I can't be there all the time.
I think you could be right plantsitter that she is panicking.
Tottwriter I think you are also right - I need to stop doing so much for her and let her deal with things by herself.