One day at a time

The day is drawing near when I have to leave my job.  I have a little over one week left to go to work every day.  I am getting very relieved but very sad.  I made the decision to exit earlier than the final date of January 14.  I had to do it.  Going to work every day is too hard on me.  It is like reliving the grief and loss each morning as I walk in the door to the building.
There are many things I will not miss about the work itself, like the late night phone calls, the decisions I had to make that were unpopular, the stress of knowing that I was responsible for the outcomes of the department, the difficult discussions I had to have with people, and other drudgery of everyone's work.
I will, however, miss the people I have worked with for 12 years.  The smiles, the warmth, the support, the friendships.  I want to find a way to take them all with me... not that I am going anywhere in particular..  just with me in my heart, as if nothing has changed.
I am unsure how to "play" this exit.  There are probably 100 people that I like and have worked with many years.  At least 30 of those people that I will think about often and at least a dozen people that I will miss seeing every day.  How do I stay in touch?  Do I just close this book and start a new one?  Do I go to each of them and trade email addresses next week?  Connect on facebook?  Get phone numbers?  Do I send a mass email next week to all of them wishing them well, asking them to stay in touch?  Or do I just slip out on my last day without acknowledgement? 
I always hoped that my presence in that company would be one that was remembered as positive.  I had always hoped when I left, that I could look back and know that I left the organization better than I found it.  I never really pictured leaving, though, so I don't have a vision for this next week.  I guess the best I can hope for is to take this next few days "one day at a time".