The lies are so cruel that is kills you slowly thinking someone could want to hurt you that bad. And when they help poison your children into hating you too.that is when you have met evil in the flesh.
As soon as you think "let me give him/her the benefit of the doubt" more than once, you probably have a toxic person in your life. It's become a rule of thumb for me. Listen to your gut and don't ignore any red flags.
The narcissist or sociopath picks their target exactly, and then destroys all the qualities that attracted them in the first place. Always jealous, always envious, always trying to destroy my life, always failing.