crazyH
How upsetting for you and such disregard for you, by your future DIL. I wonder what your son thinks about that 🤔 - is it because she thought you were not well enough to go abroad ?
I’m not wanting to upset you, but if it was me, the hurt would have lasted ages. But then, I am one of those who just overthinks and somehow find it hard to forget.
But as others, who are much better people than I am, have said to not let it get to you. Do that and maintain your relationship with your D.I.L for the sake of the GC 
Did Roxynounou say the hen party was abroad?
So many different opinions, but I could agree with Geordiegirl that maybe she saw it as being for ‘bride’s side’ only. It could be that her own mum was very keen to go, so Auntie was taken along to keep her company. Brother’s girlfriend could also be a logical invitation, who knows?
Anyway, a bit of me thinks it would be best to say you’ve seen the pictures, and would love to have gone, rather than making barbed remarks or being ‘unavailable’ for childcare. Letting these things fester and escalate can lead to estrangement, especially when you don’t know the full picture.
I remember hearing Cher saying that her mother used to tell her to ask herself if it will matter in five years’ time, and if not, let it go, it’s not worth it.