I have never been part of a writers group, but I talked to a writer who was in one. After asking many questions about her experience I remain unconvinced.
Most fiction writers are introverted loners, though not so introverted and not so much of a loner that they are serial killers. A writers pathology is neither psychopathic or sociopathic, as attractive as those disorders may seem. Creating fiction is an escape for the writer as much as it is for the reader; it therefore has its own pathology. The odd thing is that since fiction is something made up, in short a lie, it means writers tell truth through lies. An odd pathology indeed.
A writers group if I understand correctly, is people sitting around a table, each in turn reading from their work in progress and getting feedback; the one on the spot takes the good with the bad, with said writer ignoring the good as that is not helpful, but seethes with murder in his heart for the bad feedback. A wonderful story to write would be a murder mystery in which each member of a writers group is murdered until one writer is left. Naturally he writes a murder mystery based on his experience. He, of course, is the killer. This is one reason I do not belong to a writers group. I fear my pathology could be a bit skewed.
Another reason I avoid writers groups is that each member in the group is like yourself, neither a better writer, nor a worse one, though after listening to others read their stories you may feel they are better, so by the time it is your turn to share, you have developed an inferiority complex that sends you into Freudian analysis. Or you may think the others are inferior, and in this scenario you develop a condescending Kierkegaardian superman complex that sends you into Jungian analysis.
The best you can do is find one person you have absolute faith in who will guide and steer you, a mentor if you will. This may sound odd, but I read each days output of my novel in progress to my dog. If he falls asleep I rewrite, if he pays attention I know it is good. I did get in the habit though of giving him two treats after reading. He pays attention far more frequently. Then again my dog is imaginary. I am a writer. I make things up. I lie. But there is truth in my fiction.