Hi Lui,
I have this too. What I have had to do is just visit with the family for as long as I can and then go lay down and rest awhile and then come back and visit. This is how I handle Christmas, Thanksgiving etc. At first the family was all concerned -where did you go? What's going on? I just kept telling them that this is what I have to do now. I get overstimulated and I start to suffer. Now they just think of it as normal. They know I get fatigue easy and need to check out and if I can I will check back in but i may not and that is ok too.
Don't worry they will come around. I explained it once to them and then not again. They likely don't understand what I go through but they understand if you just continue with the behavior. They will come to accept it. If not, they were not worth your time in the first place.