Jealousy

My job is becoming more and more Nanny Diaryish as the weeks go on. There is so much jealousy in this house between parents, and now it seems I am contributing my own. I don't know if I would call it jealousy exactly, but a fierce Mama Bear mentality that I'm not actually entitled do. J and D have stopped fighting with eachother and are now fighting over poor S. Its like they are both tugging on her arms and for a while she thinks it is fun, but then it starts to hurt. And I just want to stand up and yell "Don't you dare hurt my baby." Lately they've taken to coming down to "play" with S at random times during the day, and I find myself growing jealous and resentful, like I'm having her stolen from me. I've been at this job for 4 months now, and while that may not seem like very long, I am totally and completely attached to this kid. Lately I've ditched "naptime" and started just taking her into her room and holding her and singing to her until she falls asleep in my arms, perfectly peaceful, and perfectly safe. I have the primal urge to protect her from all this tension raging around her. I keep feeling that I really need to detach myself, but I don't know how, or even if I can.
And then I came to a realization tonight of what the psychology behind my actions is. In a way...in the back of my consiousness...S is actually me. I have this intense desire to be nothing but a place of love for her, like a shield against everything out of our control. That maybe if I can just love her the right way for even a little while, she'll develop an immunity against what I can only see as a troubled life of privilege, appearances, and expectations. It's terribly presumptuous of me, I know. Who am I to judge? I'm the one that is already premeditating a cold, calculated, and heartless abandonment of this same child that I "love."
Sigh.