Holidays are hard on mental health, sometimes ordinarily, and Incontenience makes it worse..
There's a thread on food and chemicals, on here. I can drink a cup of coffee in the AM, maybe until 1 PM. Sugar is a no-no in the evening. The amount of liquid consumed in the evening makes a difference. No Sucrolose at any time. I've no idea what alcohol does because i can't drink it - it's incompatible with my medications. ("Oh, just a sip or it spoils the toast" turns into a pint, if you let them force it on you.) Remember, everyone is different. Maybe you can drink coffee (caffeine) or maybe not. I've shut them down with "well, that's the way it works for me." Or: "That's my story and I'm sticking to it."
Holiday dinners are like a restaurant - you can always ask for water, not coffee, probably not tea unless a herbal tea. If there are kids, maybe milk can work (socially, i mean.) Someone will reach across and pour you a cup of coffee? Just don't drink it.
Due to brain cancer (Bad luck never comes alone), water (tap water or bottled or distilled, doesn't matter) tastes like it has soap in it, to me. A squirt of Lime juice solves the taste issue, and seems to help lower the volume i use/want. Lemon works. Neither of which have calories.
Some of my family "pushes" food - like, seriously. You "have" to have a piece of Aunt Rhodie's pie or she'll cry. (She will.) .... "Just a small slice" would serve two teenage boys. ...."That isn't enough. Here, have another serving of dressing." Plop. ...."It's Christmas; once a year, ignore the calories." (This from the 350-pounder.) ....See if you can make your own servings - "I like to taste everything, so i limit how much to leave room. Everyone's cooking in this family is just so good." (A little bit of honey helps the medicine go down...)
So, invent "reasons". "Sorry, coffee just doesn't seem to agree with me, anymore." If they persist on the "whys", (If your family is as nosy as mine and think they know better than any doctor or nurse.) just shrug. Or: "The Doc doesn't know why". You have to listen to endless stories and advice about the miracle fruit that cures diabetes or whatever. Just let it in one ear and out the other. Nod. Grunt at appropriate places. Ignore. Another tactic? "I read these three articles in the scientific journals. I don't use the internet and Google for medical matters. 99% is house-pucky." "Sorry, Reader's Digest (or AARP, for that matter), don't meet the standards for scientific research."
It's all a challenge to your mental health. Maybe your spouse will let you vent on the way home - or maybe she'll pass it on (God help you).
Try meditation. Soothing music. Non-soothing music. Something!
Good Luck!