Like Christy, I find my critique groups to be a wonderful source of feedback, encouragement, and guidance. Without my critique groups (one which was formed from the members of a writing class I was in, just as Christy noted) I know I would have never completed my first novel, nor would I be as productive as I am. I've been in one group over ten years, and the other just slightly less, and the other members have become more than critiquers, but good friends, like fellow spud John Coy.
And while I greatly appreciate the community of other creators that I find in my critique groups, I also agree with Christy that I don't feel lonely at all when I am creating. Sometimes I'm frustrated, and sometimes I'm discouraged, but I never feel lonely. And when the writing or illustrating is going well, then I feel simply joyous...and very content.