My gf's mom is completely nuts and has, for years, been accusing my gf's father of cheating with every woman in the neighborhood, that he sees at the grocery store, or sometimes just women that she runs into that he doesn't even know. To the point that, on occasion, she's confronted some of these women. I think one of them actually called the police on her. A few years ago, she moved on to accusing him of gay affairs. And apparently just recently she has become convinced that their neighbor is pimping out his 15 year old daughter, and of course her husband is one of her customers.
My gf's dad is totally cool and I feel so sorry for him.