I lived across the street from a very bored stay-at-home mom whose excess idle time turned her into an insufferable busybody.
Her husband backed out of the driveway and slammed into my roommate's car parked on the curb. He apologized, gave us his insurance info, and took care of it. He was never a problem, because he accepted responsibility for what he did.
His wife, however, demanded that we never ever park any cars at the curb again, because "we can't get out of our driveway otherwise". The street was very wide - she was just completely unable to accept that the accident was her husband's fault, and figured we were somehow responsible for it, ergo we were responsible for preventing it in the future.
We told her that we would avoid parking there whenever possible, but that we still had the legal right to park on the street, and that if necessary we would still do so, and that it was her and her husband's responsibility to avoid hitting other people's legally parked cars when backing out of the driveway. She wasn't happy with that answer, but just told us we better stay out of her family's way, and stormed off.
One day, she came storming over, banging on the front door, cussing us out. We got her on our security camera saying "If you don't move that car in the next 10 minutes, I am going to total it with my truck. It'll be your fault, and you'll have to pay for the damage to my vehicle". To this, I simply responded: "I don't know whose car that is, but I didn't park it there. I have you on camera, so if you do anything to that car, I'll have to call the police and hand over this tape". She then threatened to sue me for invasion of privacy for recording her, and still insisted that we move the car, even though it wasn't our property. We just ignored her, and she did not do anything to the car - we did keep the recording though.
A few weeks later, I had a friend visit from out of town. He parked his car on the curb, and then started unloading some stuff from his trunk. She came storming out, screaming and cussing at him "I have told you repeatedly never park your car on this curb. If you don't move it, I am going to total it, and you can pay for a new goddamn car, as well as the damage you do to mine!" He tried to calm her down, and asked if there was somewhere else he could park, and she replied "You can park it in Hell, because that's where you'll be after I kill you!".
Unfortunately for her, he had his dashcam running the whole time, and it captured everything. He called the police, and she was arrested for threatening to commit vandalism and for threatening violence.
A few days later, she left a long-winded hate-letter in our mailbox. It was written as if it were an open letter from the entire neighborhood, and it basically said that "nobody knows who you are", and "Everyone wishes you would move away", and "Nobody wants you living in our neighborhood".
Thing is, she forgot about the security cameras. I took the video of her opening my mailbox -which included her taking all our letters out of the mailbox and rifling through them - and I gave them to the post office. This led to her getting arrested for a second time that week.
After that, we used her two arrests, our collection of security and dashcam footage, and her letter to get a restraining order against her that actually prohibited her from entering her own home, and then we called the police every time we saw her because she was in violation of the order.
She ended up having to live in a hotel room, and her husband came over, apologized to us, and asked if we would drop the restraining order so his wife could come home. I told him I would do it, but only if she wrote me, my wife, our roommates, and the friend of mine she threatened a 1 -page apology for her harassment - and that she would promise to never ever contact us again for any reason whatsoever moving forward.
I received no apology, and the house went on the market a week later.