I have this problem at times. I feel paranoid that people may be talking crap behind my back. I think questioning your thoughts is helpful. Being in the moment and realizing the thoughts and not worrying whether you'll judge yourself because of being harsh to yourself. It's a matter of self esteem I guess. You should realise you are worthy no matter what happens or what others say about you. There will be people who will dislike and others who will love you and stay in your life. People have spoken crap behind my back, spoke negatively in front of me, called me ugly and worse names. At the end of the day, it's partly their issues aswell and not you. If they call you ugly, it might because they aren't very happy with themselves. A happy, confident person wouldn't want to put others down. Perhaps try CBT or DBT therapy. I don't know what you deal with but be gentle with yourself and take your time. I wish you all the best.