Ok this will be long and I have NC'd as the details may out me!
My sister is getting married - she's older than me and I am very happy for her. We live in separate areas of the country and I haven't seen much of her since she met her fiancé (fair enough).
The wedding is at a hotel - very very nice. I have a DS with autism and she rang a while ago throwing ideas around (like would he cope abroad). Anyway I kind of said do whatever and I will get him through but to be aware that the timeframe she was looking at (June to Oct) was as he moved to secondary school and that we (professionals and I) were very very worried about how he would cope.
The wedding has been booked in the same week he leaves primary school. 

Clearly it's her day and we are not her main concern which is fine. I have the choice to go or not.
In addition there are lots of wider family issue - historically my sister and I meet on common ground to rise above the nonsense our family causes. She would like me to 'manage' the issues on her day so she doesn't have to... I agree she doesn't have to but I can't see why the grown ups can't manage themselves 
I don't want to go - the hassle, the preparation, up-ending my son, the family issue and not to mention the cost (hotel is £250 a night).... I just don't want to go.
I know I am being unreasonable but I wondered how much? It's a wedding and I am close family - are they ever going to speak to me again?