This is going to lead to great sex and hurt feelings.

The fact that you shouldn't have him and that your friends are all telling you it is a bad idea will just make you jump his bones as soon as you're both alone. The sense of adventure and "oh so wrongness" will almost ensure it happens. Also, he is gonna be actively trying to get in your pants too. Because it really wouldn't hurt anyone. Except it will hurt someone. Namely you.

So if you want great adventure sex over the holidays head over to bang town.

But if you want to try to keep this guy as a friend see him a couple times in groups and get a girlfriend to swear to you not to leave you alone. Keep that up for 3 years and you may not sleep together again.

Good luck!