"I've spent most of my life walking under that hovering cloud, jealousy, whose acid raindrops blurred my vision and burned holes in my heart." ~Astrid Alauda
I've seen a lot of this lately. It is rampant in the writing business and of course in many other arenas. I've been guilty of it myself. It's one thing to feel it though, it's another to act on it.
When I'm feeling jealous, I will normally find a confidante and vent. That way, I get it out without hurting feelings, without letting the target of my jealousy know I'm feeling ugly about them. I think that's okay. No one gets hurt (unless of course your confidante has a big mouth, but I think I've chosen well where confidantes are concerned).
I've also had someone come straight out and tell me they were jealous of me. That's okay too. You're being honest and you're not letting it take you over. In a sense, when you admit it, you're setting it free. As long as you admit it in a nice way.
To spew your jealousy out in a venomous, hateful diatribe is wrong. And usually, we do this to people we supposedly care about, our family, our friends, the people that are closest to us.
My suggestions, if you're think of doing this face to face, bite your tongue. If you're writing an email, get it all out, then delete it.
Jealousy is a natural human emotion, there's no way of stopping it, but you do have choices regarding how to tame the beast.