If you hadn't of mentioned that your SO no longer lives with you, I would have ventured to say you are jealous of her. I say that kindly, because I have had my own struggles with my very beautiful and deeply loved 16 year old stepdaughter, who is a typical girl teenager, and only thinks of herself, in every sense. I've had to change my perception. My way of treating her. I've had to dig deep to try and understand her. And I've struggled with jealousy in terms of her and her dad that I've had to overcome by myself. If your stepdaughter is not really factoring in your life (no longer lives with you) and is by rights, an adult, I don't see why you're wasting so many negative feelings and so much energy thinking she has it in for you. She probably doesn't really care that much at all. Or perhaps that is what upsets you.