Thank you so much to both of you for your excellent advice.
I started already. I am making a selection of people right now. Yesterday I just went over to a few people I suspected to be manipulative and said : "So what exactly is your problem?". You wouldn't believe!!!! Now I know what I wanted to know. And I know the real reason for their behaviour : official reason (you are obnoxious), real reason ("my boyfriend is far too interested in you but I forced him to distance himself from you" or "You don't want me ? you are going to pay"). I feel so relieved to know that.
I also went to a person I actually respect and just told her my frustration and that I was FED UP. She had a very decent reaction. It made her think about everything.
So that was some necessary cleaning up.
From now on, I will just tell people the way it is, the bad but also the good. Take or leave it.
I will start to look for a new job very soon coz I am unemployed anyway. I won't move. It is up to them to live with it. Now that I know the reasons, it is not MY problem anymore. The problem was the uncertainty, the doubts, you know. I can take criticism and I am indifferent to jerks, once I know they are jerks.
Also, this experience showed me who were my real friends, coz they supported me when I needed them. That is good to know. I feel much better.
Thanks for the support!