How can I fix my dogs behavior?

I have an adult lhasa apso that has started peeing in my house, on my fiance's boots, and in her car. My dog is very jealous of my fiance and is trying to break us up. She has even gone after my fiance's cat as a way to make us fight. I know my fiance does not abuse her but she tries to make me think she does. She'll cower and shake when my fiance is around and she knows I'm looking. She has even took off while my fiance is holding the leash to try to make me think she's being mean to her. When I do not react the way my dog wants me to she pees on the carpet. I know some of you will think that a dog is not capable of this type of manipulation, but I promise you, she is. I have put a diaper on her to keep her from peeing on things and I have stopped coddling her, I have spoiled her her whole life. She is kept in the crate when we are sleeping or gone so she cannot hurt the cat. I am about to my breaking point, I don't want to get rid of her but I don't think it's fair to my fiance and I to have to deal with her behavior and it is not fair to my dog to live in a house with owner's who, not only don't enjoy her, but are also resentful of her behavior. If anyone has any other ideas of what we can do to try to change this so I can keep my dog, I've had her for over 7 yrs, I would be eternally grateful.