Um... lie?
Like say, "we're going to her parents for christmas this year"
Or, "we're going to my parents for christmas this year"
Or, "we've never celebrated christmas on vacation before, we're going to do that this year"
Or, "I'm on _______ pills for _____. They thin out my blood,blah blah, blah blah, I can't _______."
Or, "I'm on _______ pills for _____ (Some psychological malfunction)__. They fix my ____ problems, though they do have nasty side-effects, like murderous/suicidal thoughts, schizophrenia, and baby torture"
These won't work via text message, no excuse will. So it needs to happen over the phone. Use a lot of large words that seem like they're related to what you're talking about. Insert your wife into the conversation, subtly, once or twice.
This will work, tell her maybe next year. Make less good lies next year and she'll feel like you're nothing but a flake.