Congratulations on getting through the party. Did anyone ask about your wife?
For now you can follow what's in the DB book, read other books about relationships and self-improvement, keep deepening your relationships with other important people in your life, grieve, and plan your next steps for both scenarios - your wife coming back and not coming back. It's just so hard. For a while I had one friend who called every night and I'd just cry. Seems you may need your true friends and family to just hold you and help you stay afloat during this crisis. It's a terrible feeling to be this broken but eventually something will happen. Your wife's affair will end and she'll reach out to you, or she'll file for divorce and you'll go through the motions, or you'll file for divorce, or something will happen. Nothing seems to make sense right now but somehow you'll pass through this misery and your life will go on. You said you're planning a holiday. Where will you go? Do you think getting away might help? A change of scenery could be good if it's to a place where you can meet new people.
If your wife messages you over Christmas it seems a simple, short, polite response would be best. For example if she says "Merry Christmas" you can say "same to you."
I'm so sorry for you Manta. Your wife has no idea what she's doing right now. Having an affair is never the right thing to do. If she didn't want to be with you she could have filed for divorce and signed the papers before embarking on a new relationship. Instead she just dove into a new relationship and left you hanging. This is not rational. I saw Sandi's response to you and what she said sounds right but there's always that small chance your wife will wake up and come home. You just have to be prepared for both scenarios and learn to live with uncertainty for a while. I hope not for too much longer.
