Feeling Alone in the Family: Struggling to Connect with My Sibling and Spouse

I really hate disassociating for hours....staring, masking so I don't have an emotional meltdown in front of my mother as I get to where her talk to her "fake daughter" for HOURS on end, constantly. Getting to listen in on half the convo because I wanna not be holed up in my room and disassociate worse. It's not like im visible, my thoughts are visible. My sibling and spouse are the shining examples of success compared to myself. They/fam all think im so excited to meet my first nephew for the first time in a few weeks and I wanna be..excited for the 7 month old baby and meet them. I only say every year that holidays are my least fave time of year to them; it was because it was the time of year I realised how alone I felt even around my cousins and sibling. Why speak when no one would listen to me anyway. Still don't listen. Oh well, I'll just be that failure.