P.K.
You know what, I don't think that ever ends with some people. Let me explain: My brother and I (even at ages 36 and 38) still have jealousy and competetive issues to work through, mostly on my part, but my whole life I've always felt like he's the better of us two. After MANY arguements, discussions, etc, I still seem to harbor some ill feelings towards him, however...would still defend him or help him if he EVER needed it, just as siblings would. I don't hate him, he's my brother and I love him, but...it's something that I've had to learn to overcome and am still learning. It's also made me the person I am. Even our mom agrees that for our whole lives, my brother and I have had some sort of wall between us, even if we hung out as friends for many years and through our highschool/college years, etc. I'd suggest that it may help if you begin teaching her the differences between she and him, and what she can do to blow off those announcances, instead of hanging onto them. She'll have to learn over time how to NOT be jealous. For instance: I learned that my jealousy is mostly about the material items he has in his life. I also learned that my brother is very shallow and materialistic, a less desired ideal, (or fault rather) in which I'm proud to say that I don't share with him, so the jealousy isn't as prevolent anymore.
Hope this helps a little.