There is something familiar to me about the way you accuse yourself of selfishness when all you are doing is trying to deal with someone who is truly selfish. Is it possible that you were raised (as I was, hence the familiar feeling) in an environment where your needs and wishes were made to seem wrong? Perhaps you were even accused of selfishness for ordinary acts of self-expression? Any time I expressed any discontent with the fact that my brother was treated better than me (which he was, he has acknowledged this himself) I was called a green-eyed monster, among other things. So I learned to shut up. But the feelings still existed, and hence I too can be triggered by people like your tenant...
Just a few thoughts..