xmas day with BD's family

Im about to celebrate xmas with my bd's family. We haven't spoken since thanksgiving except for 2 big fights him asking me if it was really over? !!! But I'm going so that LO can open presents and play with his cousins. How can I make this the least awkward?? . ...idk if BD will ask me about "us" but everytime I've seen him to drop off LO he looks upset and sad. There is no way we can ever back together !!! How can I tell him we need to work on being friends and civil to eachother.