Oh Rouky, what an awful situation for you. I can see exactly what your IC is saying, that H has compartmentalised his life, strange how they can do that. I think that perfectly describes my H too!
I can see why you're struggling to decide what to do about the wedding. On the 'hope' front, as NYGal says, it could be a chance to show what H is missing, but it would also be so heartbreaking. I also find it interesting that he wants to show his family that you can still be one big, disjointed, happy family! Cake eating again! Our WAH are so good at that! You'd think they'd be tired of cake by now.
