I have never experienced it but I've been informed that there are "trolls" on this site who bully genuine posters. I am told that you can spot them by the hurtful content of their posts. Let me assure you that the genuine suffers will NEVER be cruel. If you experience things otherwise then contact the site monitors and report them. They will be removed from the site. That doesn't completely take care of things because the bad people just sign in using another name but you can be aware of these people and ignore any negative response to your posts.
I feel for you feeling that you don't fit anywhere. It's a horrible feeling. I wonder if you've joined any of the social clubs here or have gone on any of the chats. Both places make you feel welcome and part of a nice community.
I hope you feel better soon.