A friend asked me for help with her holiday stress, and this is what I wrote:
Is there something you're eating that is affecting you? Sugar makes me feel and behave like you describe (happy one minute and weepy the next). Caffeine is also a rough ride...
Sometimes just accepting the feelings we don't want to be having can soothe us incredibly. As in: I accept that I can't accept the feelings I'm having that I don't want to have!
I wonder also about expectations - this time of year (and life in general). It can be so easy to have high expectations about how we'll feel, what we'll get done, how everyone else will feel/behave/respond, etc. Life is messy. Present moment awareness - even of the stuff we don't like, or especially of that stuff - is the only antidote I know. Along with a kindly attitude towards oneself.
I don't know if this helps, but I may go post it on my blog just in case.