Avoidance is the best. I suspect she is intellectually developmentally disabled. It sounds like she can't reason, so she manipulates like a child.
Can you think of something manipulative to say back to her, like, "You don't bring me homemade dinners because you flunked Home Ec." "You don't wash my car because you live in a pigpen." "You don't give me money because you aren't Christian enough." Something like that?
Or you could just lay it on the line, "I don't help you because ____________." (Whatever the truth may be, be blunt.) (Examples: I don't help you because you are manipulative. I don't help you because I barely know you, and from what I've seen it's not going that well. I don't help you because I don't like you very much. I don't help you because you are a pain in the rear. I don't help you because I feel uncomfortable in your presence. I don't help you because I don't like to be around you. I don't help you because you don't help me. I don't help you because you should hire someone. I don't help you because you should be able to do it yourself. I don't help you because you bore me.)
Or, "I'm an American who knows how civil cases work so since you are bent on slandering me, I am recording all future conversations with you". Most cell phones can record 24 hours total. Tends to shut people with an attitude up.