I would keep stum and carry on as normal as possible and look for signs and evidence.
I really sincerely hope there is some innocent explaination but am sat here wondering what the hell that could be.
Please dont go to him yet with what you have found. IF he is upto no good he wont admit to anything based on a wrapper and instead create some tall story.
You need to be vigilant. Watch his mobile phone behaviour. Check his pockets, computer useage etc. Does his car mileage match with where he has been etc, bank statements, cash withdrawals, receipts etc, does he hide anything in his car, does he come to bed late. Just start being vigilant and taking it all in. Think where you would hide a secret phone or sim or condoms and look but do not let him know what you are doing. Try your best to be completely normal around him.
Unfortunately (talking from personal experience) Xmas is a crap time to have your suspicians aroused. Not least cos its Xmas but because normal work/home routines are disrupted as is spending etc. This makes it harder for you to discover anything out of the norm. IE: a reciept for some perfume, could be your Xmas pressie, extra mileage may be him Xmas shopping for you etc etc. Usually if someone is cheating on a regular basis they find time to incorporate it into their usual life routine. If he always goes to the Gym on a Tuesday for example - is he really going. If he always walks the dog at 9pm is he phoning someone etc etc.
IF there is someone else on the scene on a regular basis then it is quite likely over Christmas he/she will contact one another to (boak) wish each other a happy christmas and shit! Be extra vigilant Xmas eve, Xmas morning and NYE. I have caught my cheating H out twice like this. Me and the kids sat there on our bed xmas morning with the stockings waiting for DH to come back upstairs with a cuppa for us and him taking bloody ages, because he was wishing the OW a very happy christmas! The other time it was NYE, I found a text.
I really sincerely hope you find an innocent answer.