Now the OP hasn’t got the response she wanted she’s spat her dummy out and isn’t going. Your son will likely have a lovely time without you given how unsupportive you sound.
No, she sounds at the end of her tether. Which I can understand, as my (adopted) DD1 (12) sounds very similar. She has SEN as well as attachment issues. She also refuses to pack when we go away on holiday and stays glued to her phone. In contrast, DD2 (9, her birth sibling) always wants to do her own packing and starts in advance,
It can be very frustrating at times, though we just pack for her and don’t press her to pack for herself. (Admittedly, she is younger than the OP’s DS.) Her procrastination on schooldays, however, can drive me up the wall! As can her constant arguing.
Possibly the OP will feel differently tomorrow morning, when everyone is ready to leave, but it might be the case that staying home is precisely what she needs right now, as she sounds burnt out more than anything else. It’s very difficult to feel the love at times like that.
I’m genuinely horrified at the comments from some of the other posters, however.