I suggest if you still feel that way that your brother has good qualities about him then by all means - talk to him. Maybe say something in the line with that you're sorry but you are afraid you can not due to your health reason attend the celebration at the restaurant?? Or something of the sort??

The core of all this is that you feel and have been excluded from the group of people that have been invited to his very home. I know of this feeling. If you want things sorted out or think they can be, you could ask him why you have been excluded. On the other hand if I remember it correctly that is you yourself did not want a close relationship with your sister-in-law, if my memory serves me right that is, she would send you pics of the children of the family etc and you did not want that sort of relationship with her. I'm thinking even if it his his celebration, it is her home too - maybe something there we're missing??

If you want the relationships to be improved - then even if it may be tough at first - communication is the key, and to communicate then in the right way. I would not take on 2 at the same time. I would only talk to my brother at first.

Then I would take in consideration if this is something that could very well wait til after his birthday, as this is his day or days. If so I would only write something neutral as a reply that you can not attend the celebration at the restaurant. And send him, give him a gift. I would not want him to have bad memories associated with his 70's celebrations, down to me or anyone, it's his day/days.

People can think very differently, from different perspectives about celebrations and without addressing the background story to what has led up to those thoughts, actions, perspective, and it is so easy that misunderstandings can be made. Believe me as my husband is on the autism spectrum and me being the way I am (in good and bad) social cues, norms can and are read differently, and I have learned these days not to read much into it like I use to. I use to get silent, hurt and withdraw and then when I was ready as he could see something was wrong I would then be angry with him when talking to him, and his first reaction if someone is angry was to defend himself and be angry right back, give me a ****ty attitude, which only made me to then withdraw and be hurt again, and so our evil circle was created. This why I am stressing that you have to communicate and you have to communicate in the right manner if this is to be solved, so is the other person or people or it will not be resolved, but as things has been so infected before, perhaps best to wait til it's over with?? If you have held your breath in for so long without addressing the issue it can be easy to then sound angry if, when opening up about it. I'm like that anyhow. What works best though is if you could sound neutral and ask how the thoughts went that landed in the decision that you and your family were to be invited not to the home but to the restaurant.

If you however do not want a close relationship - then it to me would be perfect if this happened, as they then can not assume or think you would when it is your time to invite them to your home along with the rest of that close-group, but then place them in the other group - the restaurant-group. Then you both know where you have each other, what sort of rule there is, if both parties are good with that??

I hope I have not offended you in any way in any of my words and thoughts, if so I apologize :) I hope all works out, that you won't feel bad about this whole thing.