The only way an asshole can get in your head is if you let them Cobra. Not sure the situation but you got to just say FUCK IT. I have a fucking dick for a neighbor, even more so than me. He is a compulsive lair, like to snoop compulsively, steal my shit and is very vindictive. He used to go through all my shit when I was not in the room. I put up cameras and caught him and he still denied denied his favorite playbook. For almost a year he tried to make me and juju uncomfortable when we are outside. It took a long time but he learned I did not give a fuck. He took my kindness for weakness now he has zero friends again.
Rather me go from passive to aggressive which I am an expert at... I stayed assertive. He can do whatever he wants as long he stays off my property and away from me.
What is sad.. he is mostly upset I wont be his friend anymore. He tried so hard to convince me he was innocent, but forgets the past and expects you to do it as well.
If I can't trust you.. get the fuck away from me.