I can also sympathize with the pressure you all are under. My family did not celebrate Thanksgiving together, though my boyfriend’s family put a lot of pressure on us to attend. The two of us got sick the week before Thanksgiving, and both tested positive for coronavirus. His parents didn’t let up on this, still insisting we have a family dinner and pushing off the importance on quarantining.
I understand the frustration you all have experienced with similar situations, and to OP, I’m very sorry that they’ve pushed an ultimatum on you. That pressure reasonably will make you feel more distant, and feel anxious when they attempt to reach out continuously. My hope is that they will soon be able to understand and respect the boundaries which you’ve set for yourself.