I am sorry this is so hard.
I am 5.5 years out from DDay (can't believe so long!) and I was remembering the 2nd Thanksgiving after DDay and how an acquaintance invited me to join her family for Thanksgiving dinner. I am sure part of me was really sad that I didn't have my own family to celebrate with. My sister and BIL were with his family, and my mom was still living back east. Of course X and XILs were no longer part of the picture.
But it was a unique holiday and very special in its own way. I was able to connect to others in a special way. I think back on that Thanksgiving with great fondness and the kindness of this woman who later became a friend.
Amidst the sadness and grief, allow some space for being open to new connections with people, new experiences.
I think if no one invited me to join them, I would volunteer at a homeless shelter or a soup kitchen. There are many many many lonely people worse off than me. Sad, but it puts things in perspective.