I can imagine the isolation you feel on this day, GS (edit: whoops, typed Tupp by mistake)....
My church does usually say something on those "trigger days" (for me it's Mother's Day, of course)...to acknowledge that not everyone has a warm and cozy family/parents feeling to celebrate, and offers a mediation or something similar that allows everyone to sit in "the space they're in."
I find M-day so deeply painful that I don't go and just stay home and grit my teeth waiting for it to be over. Church, although well meant and even conscious enough to be inclusive of those with that kind of sad memory, is so painful on those days, when I'm awash in memories of her being there with me, standing on the pew beside me when she was little so she could pretend to read the hymnal. She loved it there.
She had a tortured and painful relationship with her Dad, but loved him. And she's been torn apart ever since his death 14 years ago. Today I lit a candle for her and also spoke during "Joys and Sorrows" about her loss of him. That helped. And for every 10 people who recoil from something so harsh as an estranged child, there's at least one who asks, and who allows me to tell it like it is.
When I give it a chance, my UU church is as supportive as this board. And in 3-D! I wish you could find a 3-D community you could trust, too. You and your beautiful son deserve one. You ARE part of the human community, as much as anyone walking (or not walking).
love to you, and comfort--
Hops