Hi there, I'm sorry to hear you suffer from this paranoia.
I'm no doctor but you may have some traits of Paranoid Personality Disorder. The lack of trust you have in people, even people you know is a possible indicator of the disorder.
If you were to sit down and think about (easier said than done I know) why people would talk negatively about you or want to hurt you you'd probably struggle to come up with a perfectly logical explanation. I try to use facts in my own life, I convince myself by repeating the facts, examples to fit into your situation would be 'I didn't HEAR them talking about me' 'I haven't DONE anything to upset them'.
Have you ever spoken with a psychiatrist or suitably qualified doctor? If you haven't already, I strongly recommend doing so.
It's nothing to be ashamed of, it's more common than you think and you will find many perfectly normal people on this forum who suffer from PDD, myself included.
All the best.