Your story sounds similar to me - I also shut down an office about a year and a half ago as well - and I do miss having other people around while I'm working...
and I also have the home office problem of becoming essentially a hermit
I have a huge, really nice home office though, and kids, so it just didn't make sense for me to move out... What I have done is hired 2 part timers (students) one comes in the morning, and one in the afternoon.
The morning guy is a programmer and the afternoon guy is a writer, I basically have them doing odd jobs... anything that I really don't want to do. They have no idea what the big picture is (and I doubt they care, I pay them well for students and they're happy), but having at least one other person "in the office" keeps me consistent, and keeps me from feeling so isolated... and at least I can chat about the news to someone