I've had those times too - one Thanksgiving comes to mind immediately. It's terribly lonely to feel everyone is having fun and you're there alone.

After reading your first post, I thought your co-worker decided to stay late simply to put you at ease and to draw you out. I'm so glad she was there for you. As you go along, and you feel you're having an 'iffy' day at work, walk by her cubical and give her a slight smile. I'm sure whatever her face looks like at that moment will tell you it's alright and she's there for you. I know you don't want to open up to her, and yes, I too suggest finding someone not connected with your work to speak to.

In the mean time, I'd like to offer you a suggestion as to the puffy eyes you're going to have via the overwhelming crying that comes while you're feeling lonely during the holiday and the return to work the following day. You don't want to look upset, so if the puffies come, use Prep. H. on your lower puffy bits about 15 minutes before you leave for work and the puffies will go away. It'll help hide your upset from your co workers.

Good luck, sweetie --- time will change your loneliness. It did for me.